Merge branch 'panels'

main.go

@@ -21,15 +21,15 @@ var (
 )
 
 var theme = ui.Theme{
-	"StatusBar": tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorSilver),
+	"StatusBar": tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorLightGray),
 }
 
 var (
 	screen *tcell.Screen
 
-	menuBar      *ui.MenuBar
+	menuBar        *ui.MenuBar
-	tabContainer *ui.TabContainer
+	panelContainer *ui.PanelContainer
-	dialog       ui.Component // nil if not present (has exclusive focus)
+	dialog         ui.Component // nil if not present (has exclusive focus)
 
 	focusedComponent ui.Component = nil
 )
@@ -48,15 +48,23 @@ func showErrorDialog(title string, message string, callback func()) {
 			callback()
 		} else {
 			dialog = nil
-			changeFocus(tabContainer) // Default behavior: focus tabContainer
+			changeFocus(panelContainer) // Default behavior: focus panelContainer
 		}
 	})
 	changeFocus(dialog)
 }
 
+func getActiveTabContainer() *ui.TabContainer {
+	if panelContainer.GetSelected() != nil {
+		return panelContainer.GetSelected().(*ui.TabContainer)
+	}
+	return nil
+}
+
 // returns nil if no TextEdit is visible
 func getActiveTextEdit() *ui.TextEdit {
-	if tabContainer.GetTabCount() > 0 {
+	tabContainer := getActiveTabContainer()
+	if tabContainer != nil && tabContainer.GetTabCount() > 0 {
 		tab := tabContainer.GetTab(tabContainer.GetSelectedTabIdx())
 		te := tab.Child.(*ui.TextEdit)
 		return te
@@ -68,6 +76,7 @@ func getActiveTextEdit() *ui.TextEdit {
 func saveAs() {
 	callback := func(filePaths []string) {
 		te := getActiveTextEdit() // te should have value if we are here
+		tabContainer := getActiveTabContainer()
 		tab := tabContainer.GetTab(tabContainer.GetSelectedTabIdx())
 
 		// If we got the callback, it is safe to assume there are one or more files
@@ -89,7 +98,8 @@ func saveAs() {
 		tab.Name = filePaths[0]
 
 		dialog = nil // Hide the file selector
-		changeFocus(tabContainer)
+		changeFocus(panelContainer)
+		tab.Name = filePaths[0]
 	}
 
 	dialog = ui.NewFileSelectorDialog(
@@ -100,7 +110,7 @@ func saveAs() {
 		callback,
 		func() { // Dialog canceled
 			dialog = nil
-			changeFocus(tabContainer)
+			changeFocus(panelContainer)
 		},
 	)
 	changeFocus(dialog)
@@ -135,11 +145,13 @@ func main() {
 	var closing bool
 	sizex, sizey := s.Size()
 
-	tabContainer = ui.NewTabContainer(&theme)
+	panelContainer = ui.NewPanelContainer(&theme)
-	tabContainer.SetPos(0, 1)
+	panelContainer.SetPos(0, 1)
-	tabContainer.SetSize(sizex, sizey-2)
+	panelContainer.SetSize(sizex, sizey-2)
 
-	changeFocus(tabContainer) // tabContainer focused by default
+	panelContainer.SetSelected(ui.NewTabContainer(&theme))
+
+	changeFocus(panelContainer) // panelContainer focused by default
 
 	// Open files from command-line arguments
 	if flag.NArg() > 0 {
@@ -169,9 +181,9 @@ func main() {
 
 			textEdit := ui.NewTextEdit(screen, arg, bytes, &theme)
 			textEdit.Dirty = dirty
-			tabContainer.AddTab(arg, textEdit)
+			getActiveTabContainer().AddTab(arg, textEdit)
 		}
-		tabContainer.SetFocused(true) // Lets any opened TextEdit component know to be focused
+		panelContainer.SetFocused(true) // Lets any opened TextEdit component know to be focused
 	}
 
 	_, err = ClipInitialize(ClipExternal)
@@ -185,12 +197,18 @@ func main() {
 
 	fileMenu.AddItems([]ui.Item{&ui.ItemEntry{Name: "New File", Shortcut: "Ctrl+N", Callback: func() {
 		textEdit := ui.NewTextEdit(screen, "", []byte{}, &theme) // No file path, no contents
+		tabContainer := getActiveTabContainer()
+		if tabContainer == nil {
+			tabContainer = ui.NewTabContainer(&theme)
+			panelContainer.SetSelected(tabContainer)
+		}
 		tabContainer.AddTab("noname", textEdit)
-
-		changeFocus(tabContainer)
 		tabContainer.FocusTab(tabContainer.GetTabCount() - 1)
+		changeFocus(panelContainer)
 	}}, &ui.ItemEntry{Name: "Open...", Shortcut: "Ctrl+O", Callback: func() {
 		callback := func(filePaths []string) {
+			tabContainer := getActiveTabContainer()
+
 			var errOccurred bool
 			for _, path := range filePaths {
 				file, err := os.Open(path)
@@ -209,12 +227,16 @@ func main() {
 				}
 
 				textEdit := ui.NewTextEdit(screen, path, bytes, &theme)
+				if tabContainer == nil {
+					tabContainer = ui.NewTabContainer(&theme)
+					panelContainer.SetSelected(tabContainer)
+				}
 				tabContainer.AddTab(path, textEdit)
 			}
 
 			if !errOccurred { // Prevent hiding the error dialog
 				dialog = nil // Hide the file selector
-				changeFocus(tabContainer)
+				changeFocus(panelContainer)
 				if tabContainer.GetTabCount() > 0 {
 					tabContainer.FocusTab(tabContainer.GetTabCount() - 1)
 				}
@@ -228,7 +250,7 @@ func main() {
 			callback,
 			func() { // Dialog is canceled
 				dialog = nil
-				changeFocus(tabContainer)
+				changeFocus(panelContainer)
 			},
 		)
 		changeFocus(dialog)
@@ -250,24 +272,36 @@ func main() {
 				}
 				te.Dirty = false
 
-				changeFocus(tabContainer)
+				changeFocus(panelContainer)
 			} else {
 				saveAs()
 			}
 		}
 	}}, &ui.ItemEntry{Name: "Save As...", QuickChar: 5, Callback: saveAs}, &ui.ItemSeparator{},
 		&ui.ItemEntry{Name: "Close", Shortcut: "Ctrl+Q", Callback: func() {
-			if tabContainer.GetTabCount() > 0 {
+			tabContainer := getActiveTabContainer()
+			if tabContainer != nil && tabContainer.GetTabCount() > 0 {
 				tabContainer.RemoveTab(tabContainer.GetSelectedTabIdx())
-			} else { // No tabs open; close the editor
+			} else {
-				closing = true
+				// if the selected is root: close editor. otherwise close panel
+				if panelContainer.IsRootSelected() {
+					closing = true
+				} else {
+					panelContainer.DeleteSelected()
+				}
 			}
 		}}})
 
 	panelMenu := ui.NewMenu("Panel", 0, &theme)
 
-	panelMenu.AddItems([]ui.Item{&ui.ItemEntry{Name: "Focus Up", QuickChar: -1, Shortcut: "Alt+Up", Callback: func() {
+	panelMenu.AddItems([]ui.Item{&ui.ItemEntry{Name: "Focus Next", Shortcut: "Alt+.", Callback: func() {
-
+		panelContainer.SelectNext()
+		changeFocus(panelContainer)
+	}}, &ui.ItemEntry{Name: "Focus Prev", Shortcut: "Alt+,", Callback: func() {
+		panelContainer.SelectPrev()
+		changeFocus(panelContainer)
+	}}, &ui.ItemEntry{Name: "Focus Up", QuickChar: -1, Shortcut: "Alt+Up", Callback: func() {
+		
 	}}, &ui.ItemEntry{Name: "Focus Down", QuickChar: -1, Shortcut: "Alt+Down", Callback: func() {
 
 	}}, &ui.ItemEntry{Name: "Focus Left", QuickChar: -1, Shortcut: "Alt+Left", Callback: func() {
@@ -275,19 +309,33 @@ func main() {
 	}}, &ui.ItemEntry{Name: "Focus Right", QuickChar: -1, Shortcut: "Alt+Right", Callback: func() {
 
 	}}, &ui.ItemSeparator{}, &ui.ItemEntry{Name: "Split Top", QuickChar: 6, Callback: func() {
-
+		panelContainer.SplitSelected(ui.SplitVertical, ui.NewTabContainer(&theme))
+		panelContainer.SwapNeighborsSelected()
+		panelContainer.SelectPrev()
+		changeFocus(panelContainer)
 	}}, &ui.ItemEntry{Name: "Split Bottom", QuickChar: 6, Callback: func() {
-
+		panelContainer.SplitSelected(ui.SplitVertical, ui.NewTabContainer(&theme))
+		panelContainer.SelectNext()
+		changeFocus(panelContainer)
 	}}, &ui.ItemEntry{Name: "Split Left", QuickChar: 6, Callback: func() {
-
+		panelContainer.SplitSelected(ui.SplitHorizontal, ui.NewTabContainer(&theme))
+		panelContainer.SwapNeighborsSelected()
+		panelContainer.SelectPrev()
+		changeFocus(panelContainer)
 	}}, &ui.ItemEntry{Name: "Split Right", QuickChar: 6, Callback: func() {
-
+		panelContainer.SplitSelected(ui.SplitHorizontal, ui.NewTabContainer(&theme))
+		panelContainer.SelectNext()
+		changeFocus(panelContainer)
 	}}, &ui.ItemSeparator{}, &ui.ItemEntry{Name: "Move", Shortcut: "Ctrl+M", Callback: func() {
 
 	}}, &ui.ItemEntry{Name: "Resize", Shortcut: "Ctrl+R", Callback: func() {
 
-	}}, &ui.ItemEntry{Name: "Float", Callback: func() {
+	}}, &ui.ItemEntry{Name: "Toggle Floating", Callback: func() {
-
+		panelContainer.FloatSelected()
+		if !panelContainer.GetFloatingFocused() {
+			panelContainer.SetFloatingFocused(true)
+		}
+		changeFocus(panelContainer)
 	}}})
 
 	editMenu := ui.NewMenu("Edit", 0, &theme)
@@ -305,7 +353,7 @@ func main() {
 				te.Delete(false) // Delete selection
 			}
 			if err == nil { // Prevent hiding error dialog
-				changeFocus(tabContainer)
+				changeFocus(panelContainer)
 			}
 		}
 	}}, &ui.ItemEntry{Name: "Copy", Shortcut: "Ctrl+C", Callback: func() {
@@ -320,7 +368,7 @@ func main() {
 				}
 			}
 			if err == nil {
-				changeFocus(tabContainer)
+				changeFocus(panelContainer)
 			}
 		}
 	}}, &ui.ItemEntry{Name: "Paste", Shortcut: "Ctrl+V", Callback: func() {
@@ -331,7 +379,7 @@ func main() {
 				showErrorDialog("Clipboard Failure", fmt.Sprintf("%v", err), nil)
 			} else {
 				te.Insert(contents)
-				changeFocus(tabContainer)
+				changeFocus(panelContainer)
 			}
 		}
 	}}, &ui.ItemSeparator{}, &ui.ItemEntry{Name: "Select All", QuickChar: 7, Shortcut: "Ctrl+A", Callback: func() {
@@ -354,12 +402,12 @@ func main() {
 				te.SetLineCol(line-1, 0)
 				// Hide dialog
 				dialog = nil
-				changeFocus(tabContainer)
+				changeFocus(panelContainer)
 			}
 			dialog = NewGotoLineDialog(screen, &theme, callback, func() {
 				// Dialog canceled
 				dialog = nil
-				changeFocus(tabContainer)
+				changeFocus(panelContainer)
 			})
 			changeFocus(dialog)
 		}
@@ -378,10 +426,8 @@ func main() {
 		//ui.DrawRect(screen, 0, 0, sizex, sizey, '▚', tcell.Style{}.Foreground(tcell.ColorGrey).Background(tcell.ColorBlack))
 		ui.DrawRect(s, 0, 1, sizex, sizey-1, ' ', tcell.Style{}.Background(tcell.ColorBlack))
 
-		if tabContainer.GetTabCount() > 0 { // Draw the tab container only if a tab is open
+		panelContainer.Draw(s)
-			tabContainer.Draw(s)
+		menuBar.Draw(s)
-		}
-		menuBar.Draw(s) // Always draw the menu bar
 
 		if dialog != nil {
 			// Update fileSelector dialog pos and size
@@ -394,10 +440,7 @@ func main() {
 
 		// Draw statusbar
 		ui.DrawRect(s, 0, sizey-1, sizex, 1, ' ', theme["StatusBar"])
-		if tabContainer.GetTabCount() > 0 {
+		if te := getActiveTextEdit(); te != nil {
-			focusedTab := tabContainer.GetTab(tabContainer.GetSelectedTabIdx())
-			te := focusedTab.Child.(*ui.TextEdit)
-
 			var delim string
 			if te.IsCRLF {
 				delim = "CRLF"
@@ -425,17 +468,17 @@ func main() {
 			sizex, sizey = s.Size()
 
 			menuBar.SetSize(sizex, 1)
-			tabContainer.SetSize(sizex, sizey-2)
+			panelContainer.SetSize(sizex, sizey-2)
 
 			s.Sync() // Redraw everything
 		case *tcell.EventKey:
 			// On Escape, we change focus between editor and the MenuBar.
 			if dialog == nil {
 				if ev.Key() == tcell.KeyEscape {
-					if focusedComponent == tabContainer {
+					if focusedComponent == panelContainer {
 						changeFocus(menuBar)
 					} else {
-						changeFocus(tabContainer)
+						changeFocus(panelContainer)
 					}
 				}
 

ui/buffer/language.go

@@ -4,6 +4,7 @@ type Syntax uint8
 
 const (
 	Default Syntax = iota
+	Column // Not necessarily a Syntax; useful for Colorscheming editor column
 	Keyword
 	String
 	Special

ui/component.go

@@ -15,8 +15,8 @@ type Component interface {
 	// A component knows its position and size, which is used to draw itself in
 	// its bounding rectangle.
 	Draw(tcell.Screen)
-	// Components can be focused, which may affect how it handles events. For
+	// Components can be focused, which may affect how it handles events or draws.
-	// example, when a button is focused, the Return key may be pressed to
+	// For example, when a button is focused, the Return key may be pressed to
 	// activate the button.
 	SetFocused(bool)
 	// Applies the theme to the component and all of its children.

ui/menu.go

@@ -148,7 +148,12 @@ func (b *MenuBar) CursorRight() {
 
 // Draw renders the MenuBar and its sub-menus.
 func (b *MenuBar) Draw(s tcell.Screen) {
-	normalStyle := b.theme.GetOrDefault("MenuBar")
+	var normalStyle tcell.Style
+	if b.focused {
+		normalStyle = b.theme.GetOrDefault("MenuBarFocused")
+	} else {
+		normalStyle = b.theme.GetOrDefault("MenuBar")
+	}
 
 	// Draw menus based on whether b.focused and which is selected
 	DrawRect(s, b.x, b.y, b.width, 1, ' ', normalStyle)
@@ -156,7 +161,8 @@ func (b *MenuBar) Draw(s tcell.Screen) {
 	for i, item := range b.menus {
 		sty := normalStyle
 		if b.focused && b.selected == i {
-			sty = b.theme.GetOrDefault("MenuBarSelected") // Use special style for selected item
+			fg, bg, attr := normalStyle.Decompose()
+			sty = tcell.Style{}.Foreground(bg).Background(fg).Attributes(attr)
 		}
 
 		str := fmt.Sprintf(" %s ", item.Name)

ui/panel.go

@@ -0,0 +1,227 @@
+package ui
+
+import "github.com/gdamore/tcell/v2"
+
+// A PanelKind describes how to interpret the fields of a Panel.
+type PanelKind uint8
+
+const (
+	PanelKindEmpty     PanelKind = iota
+	PanelKindSingle              // Single item. Takes up all available space
+	PanelKindSplitVert           // Items are above or below eachother
+	PanelKindSplitHor            // Items are left or right of eachother
+)
+
+// A Panel represents a container for a split view between two items. The Kind
+// tells how to interpret the Left and Right fields. The SplitAt is the column
+// between 0 and width or height, representing the position of the split between
+// the Left and Right, respectively.
+//
+// If the Kind is equal to PanelKindEmpty, then both Left and Right are nil.
+// If the Kind is equal to PanelKindSingle, then only Left has value,
+//   and its value will NOT be of type Panel. The SplitAt will not be used,
+//   as the Left will take up the whole space.
+// If the Kind is equal to PanelKindSplitVert, then both Left and Right will
+//   have value, and they will both have to be of type Panel. The split will
+//   be represented vertically, and the SplitAt spans 0 to height; top to bottom,
+//   respectively.
+// If the Kind is equal to PanelKindSplitHor, then both Left and Right will
+//   have value, and they will both have to be of type Panel. The split will
+//   be represented horizontally, and the SplitAt spans 0 to width; left to right.
+type Panel struct {
+	Parent  *Panel
+	Left    Component
+	Right   Component
+	SplitAt int
+	Kind    PanelKind
+	Focused bool
+
+	x, y   int
+	width  int
+	height int
+}
+
+// UpdateSplits uses the position and size of the Panel, along with its Weight
+// and Kind, to appropriately size and place its children. It calls UpdateSplits()
+// on its child Panels.
+func (p *Panel) UpdateSplits() {
+	switch p.Kind {
+	case PanelKindSingle:
+		p.Left.SetPos(p.x, p.y)
+		p.Left.SetSize(p.width, p.height)
+	case PanelKindSplitVert:
+		p.Left.SetPos(p.x, p.y)
+		p.Left.SetSize(p.width, p.SplitAt)
+		p.Right.SetPos(p.x, p.y+p.SplitAt)
+		p.Right.SetSize(p.width, p.height-p.SplitAt)
+
+		p.Left.(*Panel).UpdateSplits()
+		p.Right.(*Panel).UpdateSplits()
+	case PanelKindSplitHor:
+		p.Left.SetPos(p.x, p.y)
+		p.Left.SetSize(p.SplitAt, p.height)
+		p.Right.SetPos(p.x+p.SplitAt, p.y)
+		p.Right.SetSize(p.width-p.SplitAt, p.height)
+
+		p.Left.(*Panel).UpdateSplits()
+		p.Right.(*Panel).UpdateSplits()
+	}
+}
+
+// Same as EachLeaf, but returns true if any call to `f` returned true.
+func (p *Panel) eachLeaf(rightMost bool, f func(*Panel) bool) bool {
+	switch p.Kind {
+	case PanelKindEmpty:
+		fallthrough
+	case PanelKindSingle:
+		return f(p)
+
+	case PanelKindSplitVert:
+		fallthrough
+	case PanelKindSplitHor:
+		if rightMost {
+			if p.Right.(*Panel).eachLeaf(rightMost, f) {
+				return true
+			}
+			return p.Left.(*Panel).eachLeaf(rightMost, f)
+		} else {
+			if p.Left.(*Panel).eachLeaf(rightMost, f) {
+				return true
+			}
+			return p.Right.(*Panel).eachLeaf(rightMost, f)
+		}
+
+	default:
+		return false
+	}
+}
+
+// EachLeaf visits the entire tree, and calls function `f` at each leaf Panel.
+// If the function `f` returns true, then visiting stops. if `rtl` is true,
+// the tree is traversed in right-most order. The default is to traverse
+// in left-most order.
+//
+// The caller of this function can safely assert that Panel's Kind is always
+// either `PanelKindSingle` or `PanelKindEmpty`.
+func (p *Panel) EachLeaf(rightMost bool, f func(*Panel) bool) {
+	p.eachLeaf(rightMost, f)
+}
+
+// IsLeaf returns whether the Panel is a leaf or not. A leaf is a panel with
+// Kind `PanelKindEmpty` or `PanelKindSingle`.
+func (p *Panel) IsLeaf() bool {
+	switch p.Kind {
+	case PanelKindEmpty:
+		fallthrough
+	case PanelKindSingle:
+		return true
+	default:
+		return false
+	}
+}
+
+func (p *Panel) Draw(s tcell.Screen) {
+	switch p.Kind {
+	case PanelKindSplitVert:
+		fallthrough
+	case PanelKindSplitHor:
+		p.Right.Draw(s)
+		fallthrough
+	case PanelKindSingle:
+		p.Left.Draw(s)
+	}
+}
+
+// SetFocused sets this Panel's Focused field to `v`. Then, if the Panel's Kind
+// is PanelKindSingle, it sets its child (not a Panel) focused to `v`, also.
+func (p *Panel) SetFocused(v bool) {
+	p.Focused = v
+	switch p.Kind {
+	case PanelKindSplitVert:
+		fallthrough
+	case PanelKindSplitHor:
+		p.Right.SetFocused(v)
+		fallthrough
+	case PanelKindSingle:
+		p.Left.SetFocused(v)
+	}
+}
+
+func (p *Panel) SetTheme(theme *Theme) {
+	switch p.Kind {
+	case PanelKindSplitVert:
+		fallthrough
+	case PanelKindSplitHor:
+		p.Right.SetTheme(theme)
+		fallthrough
+	case PanelKindSingle:
+		p.Left.SetTheme(theme)
+	}
+}
+
+// GetPos returns the position of the panel.
+func (p *Panel) GetPos() (int, int) {
+	return p.width, p.height
+}
+
+// SetPos sets the position of the panel.
+func (p *Panel) SetPos(x, y int) {
+	p.x, p.y = x, y
+}
+
+// GetMinSize returns the combined minimum sizes of the Panel's children.
+func (p *Panel) GetMinSize() (int, int) {
+	switch p.Kind {
+	case PanelKindSingle:
+		return p.Left.GetMinSize()
+	case PanelKindSplitVert:
+		// use max width, add heights
+		lWidth, lHeight := p.Left.GetMinSize()
+		rWidth, rHeight := p.Right.GetMinSize()
+		return Max(lWidth, rWidth), lHeight + rHeight
+	case PanelKindSplitHor:
+		// use max height, add widths
+		lWidth, lHeight := p.Left.GetMinSize()
+		rWidth, rHeight := p.Right.GetMinSize()
+		return lWidth + rWidth, Max(lHeight, rHeight)
+	default:
+		return 0, 0
+	}
+}
+
+func (p *Panel) GetSize() (int, int) {
+	return p.width, p.height
+}
+
+// SetSize sets the Panel size to the given width, and height. It will not check
+// against GetMinSize() because it may be costly to do so. SetSize clamps the
+// Panel's SplitAt to be within the new size of the Panel.
+func (p *Panel) SetSize(width, height int) {
+	p.width, p.height = width, height
+	switch p.Kind {
+	case PanelKindSplitVert:
+		p.SplitAt = Min(p.SplitAt, height)
+	case PanelKindSplitHor:
+		p.SplitAt = Min(p.SplitAt, width)
+	}
+}
+
+// HandleEvent propogates the event to all children, calling HandleEvent()
+// on left-most items. As usual: returns true if handled, false if unhandled.
+// This function relies on the behavior of the child Components to only handle
+// events if they are focused.
+func (p *Panel) HandleEvent(event tcell.Event) bool {
+	switch p.Kind {
+	case PanelKindSingle:
+		return p.Left.HandleEvent(event)
+	case PanelKindSplitVert:
+		fallthrough
+	case PanelKindSplitHor:
+		if p.Left.HandleEvent(event) {
+			return true
+		}
+		return p.Right.HandleEvent(event)
+	default:
+		return false
+	}
+}

ui/panelcontainer.go

@@ -0,0 +1,337 @@
+package ui
+
+import "github.com/gdamore/tcell/v2"
+
+type SplitKind uint8
+
+const (
+	SplitVertical SplitKind = SplitKind(PanelKindSplitVert) + iota
+	SplitHorizontal
+)
+
+type PanelContainer struct {
+	root                    *Panel
+	floating                []*Panel
+	selected                **Panel // Only Panels with PanelKindSingle
+	lastNonFloatingSelected **Panel // Used only when focused on floating Panels
+	floatingMode            bool    // True if 'selected' is part of a floating Panel
+	focused                 bool
+	theme                   *Theme
+}
+
+func NewPanelContainer(theme *Theme) *PanelContainer {
+	root := &Panel{Kind: PanelKindEmpty}
+	return &PanelContainer{
+		root:     root,
+		floating: make([]*Panel, 0, 3),
+		selected: &root,
+		theme:    theme,
+	}
+}
+
+// ClearSelected makes the selected Panel empty, but does not delete it from
+// the tree.
+func (c *PanelContainer) ClearSelected() Component {
+	item := (**c.selected).Left
+	(**c.selected).Left = nil
+	(**c.selected).Kind = PanelKindEmpty
+	if p := (**c.selected).Parent; p != nil {
+		p.UpdateSplits()
+	}
+	return item
+}
+
+// changeSelected sets c.selected to `new`. It also refocuses the Panel.
+// Prefer to use this as opposed to performing the instructions manually.
+func (c *PanelContainer) changeSelected(new **Panel) {
+	if c.focused {
+		(*c.selected).SetFocused(false)
+	}
+	c.selected = new
+	if c.focused {
+		(*c.selected).SetFocused(true)
+	}
+}
+
+// DeleteSelected deletes the selected Panel and returns its child Component.
+// If the selected Panel is the root Panel, ClearSelected() is called, instead.
+func (c *PanelContainer) DeleteSelected() Component {
+	if !(*c.selected).IsLeaf() {
+		panic("selected is not leaf")
+	}
+
+	// If selected is the root, just make it empty
+	if *c.selected == c.root {
+		return c.ClearSelected()
+	} else {
+		item := (**c.selected).Left
+		p := (**c.selected).Parent
+
+		if p != nil {
+			if *c.selected == (*p).Left { // If we're deleting the parent's Left
+				(*p).Left = (*p).Right
+				(*p).Right = nil
+			} else { // Deleting parent's Right
+				(*p).Right = nil
+			}
+
+			if (*p).Left != nil {
+				// Parent becomes the Left panel
+				panel := (*p).Left.(*Panel)
+				(*p).Left = (*panel).Left
+				(*p).Right = (*panel).Right
+				(*p).Kind = (*panel).Kind
+				(*p).SplitAt = (*panel).SplitAt
+			} else {
+				(*p).Kind = PanelKindEmpty
+			}
+
+			// Decide what Panel to select next
+			if !(*p).IsLeaf() { // If the new panel was a split panel...
+				// Select the leftmost child of it
+				(*p).EachLeaf(false, func(l *Panel) bool { c.changeSelected(&l); return true })
+			} else {
+				c.changeSelected(&p)
+			}
+
+			(*p).UpdateSplits()
+		} else if c.floatingMode { // Deleting a floating Panel without a parent
+			c.floating[0] = nil
+			copy(c.floating, c.floating[1:])            // Shift items to front
+			c.floating = c.floating[:len(c.floating)-1] // Shrink slice's len by one
+
+			if len(c.floating) <= 0 {
+				c.SetFloatingFocused(false)
+			} else {
+				c.changeSelected(&c.floating[0])
+			}
+		} else {
+			panic("Panel does not have parent and is not floating")
+		}
+
+		return item
+	}
+}
+
+// SwapNeighborsSelected swaps two Left and Right child Panels of a vertical or
+// horizontally split Panel. This is necessary to achieve a "split top" or
+// "split left" effect, as Panels only split open to the bottom or right.
+func (c *PanelContainer) SwapNeighborsSelected() {
+	parent := (**c.selected).Parent
+	if parent != nil {
+		left := (*parent).Left
+		(*parent).Left = parent.Right
+		(*parent).Right = left
+		parent.UpdateSplits() // Updates position and size of reordered children
+	}
+}
+
+// Turns the selected Panel into a split panel, moving its contents to its Left field,
+// and putting the given Panel at the Right field. `panel` cannot be nil.
+func (c *PanelContainer) splitSelectedWithPanel(kind SplitKind, panel *Panel) {
+	(**c.selected).Left = &Panel{Parent: *c.selected, Left: (**c.selected).Left, Kind: (**c.selected).Kind}
+	(**c.selected).Right = panel
+	(**c.selected).Right.(*Panel).Parent = *c.selected
+
+	// Update parent's split information
+	(**c.selected).Kind = PanelKind(kind)
+	if kind == SplitVertical {
+		(**c.selected).SplitAt = (**c.selected).height / 2
+	} else {
+		(**c.selected).SplitAt = (**c.selected).width / 2
+	}
+	(*c.selected).UpdateSplits()
+
+	// Change selected from parent to the previously selected Panel on the Left
+	panel = (**c.selected).Left.(*Panel)
+	c.changeSelected(&panel)
+}
+
+// SplitSelected splits the selected Panel with the given Component `item`.
+// The type of split (vertical or horizontal) is determined with the `kind`.
+// If `item` is nil, the new Panel will be of kind empty.
+func (c *PanelContainer) SplitSelected(kind SplitKind, item Component) {
+	if !(*c.selected).IsLeaf() {
+		panic("selected is not leaf")
+	}
+
+	if item == nil {
+		c.splitSelectedWithPanel(kind, &Panel{Parent: *c.selected, Kind: PanelKindEmpty})
+	} else {
+		c.splitSelectedWithPanel(kind, &Panel{Parent: *c.selected, Left: item, Kind: PanelKindSingle})
+	}
+}
+
+func (c *PanelContainer) IsRootSelected() bool {
+	return *c.selected == c.root
+}
+
+func (c *PanelContainer) GetSelected() Component {
+	if !(*c.selected).IsLeaf() {
+		panic("selected is not leaf")
+	}
+	return (**c.selected).Left
+}
+
+func (c *PanelContainer) SetSelected(item Component) {
+	if !(*c.selected).IsLeaf() {
+		panic("selected is not leaf")
+	}
+
+	(**c.selected).Left = item
+	(**c.selected).Kind = PanelKindSingle
+	(*c.selected).UpdateSplits()
+}
+
+func (c *PanelContainer) raiseFloating(idx int) {
+	item := c.floating[idx]
+	copy(c.floating[1:], c.floating[:idx]) // Shift all items before idx right
+	c.floating[0] = item
+}
+
+// GetFloatingFocused returns true if a floating window is selected or focused.
+func (c *PanelContainer) GetFloatingFocused() bool {
+	return c.floatingMode
+}
+
+// SetFloatingFocused sets whether the floating Panels are focused. When true,
+// the current Panel will be unselected and the front floating Panel will become
+// the new selected if there any floating windows. If false, the same, but the
+// last selected non-floating Panel will become focused.
+//
+// The returned boolean is whether floating windows were able to be focused. If
+// there are no floating windows when trying to focus them, this will inevitably
+// return false, for example.
+func (c *PanelContainer) SetFloatingFocused(v bool) bool {
+	if v {
+		if len(c.floating) > 0 {
+			c.lastNonFloatingSelected = c.selected
+			c.changeSelected(&c.floating[0])
+			c.floatingMode = true
+			return true
+		}
+	} else {
+		c.changeSelected(c.lastNonFloatingSelected)
+		c.floatingMode = false
+	}
+	return false
+}
+
+// FloatSelected makes the selected Panel floating. This function does not focus
+// the newly floated Panel. To focus the floating panel, call SetFloatingFocused().
+func (c *PanelContainer) FloatSelected() {
+	if !(*c.selected).IsLeaf() {
+		panic("selected is not leaf")
+	}
+
+	if c.floatingMode {
+		return
+	}
+
+	c.DeleteSelected()
+	(**c.selected).Parent = nil
+	(*c.selected).UpdateSplits()
+
+	c.floating = append(c.floating, *c.selected)
+	c.raiseFloating(len(c.floating) - 1)
+}
+
+// UnfloatSelected moves any selected floating Panel to the normal tree that is
+// accessible in the standard focus mode. This function will cause focus to go to
+// the normal tree if there are no remaining floating windows after the operation.
+//
+// Like SetFloatingFocused(), the boolean returned is whether the PanelContainer
+// is focusing floating windows after the operation.
+func (c *PanelContainer) UnfloatSelected(kind SplitKind) bool {
+	if !(*c.selected).IsLeaf() {
+		panic("selected is not leaf")
+	}
+
+	if !c.floatingMode {
+		return false
+	}
+
+	c.DeleteSelected()
+	c.SetFloatingFocused(false)
+	c.splitSelectedWithPanel(kind, *c.selected)
+
+	// Try to return to floating focus
+	return c.SetFloatingFocused(true)
+}
+
+func (c *PanelContainer) selectNext(rightMost bool) {
+	var nextIsIt bool
+	c.root.EachLeaf(rightMost, func(p *Panel) bool {
+		if nextIsIt {
+			c.changeSelected(&p)
+			nextIsIt = false
+			return true
+		} else if p == *c.selected {
+			nextIsIt = true
+		}
+		return false
+	})
+
+	// This boolean must be false if we found the next leaf.
+	// Therefore, if it is true, c.selected was the last leaf
+	// of the tree. We need to wrap around to the first leaf.
+	if nextIsIt {
+		// This gets the first leaf in left-most or right-most order
+		c.root.EachLeaf(rightMost, func(p *Panel) bool { c.changeSelected(&p); return true })
+	}
+}
+
+func (c *PanelContainer) SelectNext() {
+	c.selectNext(false)
+}
+
+func (c *PanelContainer) SelectPrev() {
+	c.selectNext(true)
+}
+
+func (c *PanelContainer) Draw(s tcell.Screen) {
+	c.root.Draw(s)
+	for i := len(c.floating) - 1; i >= 0; i-- {
+		c.floating[i].Draw(s)
+	}
+}
+
+func (c *PanelContainer) SetFocused(v bool) {
+	c.focused = v
+	(*c.selected).SetFocused(v)
+}
+
+func (c *PanelContainer) SetTheme(theme *Theme) {
+	c.theme = theme
+	c.root.SetTheme(theme)
+	for i := range c.floating {
+		c.floating[i].SetTheme(theme)
+	}
+}
+
+func (c *PanelContainer) GetPos() (int, int) {
+	return c.root.GetPos()
+}
+
+func (c *PanelContainer) SetPos(x, y int) {
+	c.root.SetPos(x, y)
+	c.root.UpdateSplits()
+}
+
+func (c *PanelContainer) GetMinSize() (int, int) {
+	return c.root.GetMinSize()
+}
+
+func (c *PanelContainer) GetSize() (int, int) {
+	return c.root.GetSize()
+}
+
+func (c *PanelContainer) SetSize(width, height int) {
+	c.root.SetSize(width, height)
+	c.root.UpdateSplits()
+}
+
+func (c *PanelContainer) HandleEvent(event tcell.Event) bool {
+	// Call handle event on selected Panel
+	return (*c.selected).HandleEvent(event)
+}

ui/tabcontainer.go

@@ -86,23 +86,29 @@ func (c *TabContainer) GetTab(idx int) *Tab {
 
 // Draw will draws the border of the BoxContainer, then it draws its child component.
 func (c *TabContainer) Draw(s tcell.Screen) {
+	var styFocused tcell.Style
+	if c.focused {
+		styFocused = c.theme.GetOrDefault("TabContainerFocused")
+	} else {
+		styFocused = c.theme.GetOrDefault("TabContainer")
+	}
+
 	// Draw outline
-	DrawRectOutlineDefault(s, c.x, c.y, c.width, c.height, c.theme.GetOrDefault("TabContainer"))
+	DrawRectOutlineDefault(s, c.x, c.y, c.width, c.height, styFocused)
 
 	combinedTabLength := 0
-	for _, tab := range c.children {
+	for i := range c.children {
-		combinedTabLength += len(tab.Name) + 2 // 2 for padding
+		combinedTabLength += len(c.children[i].Name) + 2 // 2 for padding
 	}
 	combinedTabLength += len(c.children) - 1 // add for spacing between tabs
 
 	// Draw tabs
-	col := c.x + c.width/2 - combinedTabLength/2 - 1 // Starting column
+	col := c.x + c.width/2 - combinedTabLength/2 // Starting column
 	for i, tab := range c.children {
-		var sty tcell.Style
+		sty := styFocused
 		if c.selected == i {
-			sty = c.theme.GetOrDefault("TabSelected")
+			fg, bg, attr := styFocused.Decompose()
-		} else {
+			sty = tcell.Style{}.Foreground(bg).Background(fg).Attributes(attr)
-			sty = c.theme.GetOrDefault("Tab")
 		}
 
 		var dirty bool
@@ -118,7 +124,7 @@ func (c *TabContainer) Draw(s tcell.Screen) {
 
 		str := fmt.Sprintf(" %s ", name)
 
-		DrawStr(s, c.x+col, c.y, str, sty)
+		DrawStr(s, col, c.y, str, sty)
 		col += len(str) + 1 // Add one for spacing between tabs
 	}
 

ui/textedit.go

@@ -42,6 +42,7 @@ type TextEdit struct {
 	curx, cury       int // Zero-based: cursor points before the character at that position.
 	prevCurCol       int // Previous maximum column the cursor was at, when the user pressed left or right
 	scrollx, scrolly int // X and Y offset of view, known as scroll
+	theme            *Theme
 
 	selection  Region // Selection: selectMode determines if it should be used
 	selectMode bool   // Whether the user is actively selecting text
@@ -115,6 +116,7 @@ loop:
 
 	colorscheme := &buffer.Colorscheme{
 		buffer.Default: tcell.Style{}.Foreground(tcell.ColorLightGray).Background(tcell.ColorBlack),
+		buffer.Column:  tcell.Style{}.Foreground(tcell.ColorDarkGray).Background(tcell.ColorBlack),
 		buffer.Comment: tcell.Style{}.Foreground(tcell.ColorGray).Background(tcell.ColorBlack),
 		buffer.String:  tcell.Style{}.Foreground(tcell.ColorOlive).Background(tcell.ColorBlack),
 		buffer.Keyword: tcell.Style{}.Foreground(tcell.ColorNavy).Background(tcell.ColorBlack),
@@ -265,6 +267,20 @@ func (t *TextEdit) GetLineCol() (int, int) {
 	return t.cury, t.curx
 }
 
+// The same as updateTerminalCursor but the caller can provide the tabOffset to
+// save the original function a calculation.
+func (t *TextEdit) updateTerminalCursorNoHelper(columnWidth, tabOffset int) {
+	(*t.screen).ShowCursor(t.x+columnWidth+t.curx+tabOffset-t.scrollx, t.y+t.cury-t.scrolly)
+}
+
+// updateTerminalCursor sets the position of the cursor with the cursor position
+// properties of the TextEdit. Always sends a signal to *show* the cursor.
+func (t *TextEdit) updateTerminalCursor() {
+	columnWidth := t.getColumnWidth()
+	tabOffset := t.getTabCountInLineAtCol(t.cury, t.curx) * (t.TabSize - 1)
+	t.updateTerminalCursorNoHelper(columnWidth, tabOffset)
+}
+
 // SetLineCol sets the cursor line and column position. Zero is origin for both.
 // If `line` is out of bounds, `line` will be clamped to the closest available line.
 // If `col` is out of bounds, `col` will be clamped to the closest column available for the line.
@@ -297,9 +313,8 @@ func (t *TextEdit) SetLineCol(line, col int) {
 
 	t.cury, t.curx = line, col
 	if t.focused && !t.selectMode {
-		(*t.screen).ShowCursor(t.x+columnWidth+col+tabOffset-t.scrollx, t.y+line-t.scrolly)
+		// Update terminal cursor position
-	} else {
+		t.updateTerminalCursorNoHelper(columnWidth, tabOffset)
-		(*t.screen).HideCursor()
 	}
 }
 
@@ -357,10 +372,10 @@ func (t *TextEdit) CursorRight() {
 
 // getColumnWidth returns the width of the line numbers column if it is present.
 func (t *TextEdit) getColumnWidth() int {
-	columnWidth := 0
+	var columnWidth int
 	if t.LineNumbers {
 		// Set columnWidth to max count of line number digits
-		columnWidth = Max(2, len(strconv.Itoa(t.Buffer.Lines()))) // Column has minimum width of 2
+		columnWidth = Max(3, 1+len(strconv.Itoa(t.Buffer.Lines()))) // Column has minimum width of 2
 	}
 	return columnWidth
 }
@@ -382,7 +397,7 @@ func (t *TextEdit) Draw(s tcell.Screen) {
 	bufferLines := t.Buffer.Lines()
 
 	selectedStyle := t.theme.GetOrDefault("TextEditSelected")
-	columnStyle := t.theme.GetOrDefault("TextEditColumn")
+	columnStyle := t.Highlighter.Colorscheme.GetStyle(buffer.Column)
 
 	t.Highlighter.UpdateInvalidatedLines(t.scrolly, t.scrolly+(t.height-1))
 
@@ -406,22 +421,7 @@ func (t *TextEdit) Draw(s tcell.Screen) {
 			var origLineBytes []byte = t.Buffer.Line(line)
 			var lineBytes []byte = origLineBytes // Line to be drawn
 
-			// When iterating lineTabs: the value at i is
-			// the rune index the tab was found at.
-			//			var lineTabs  [128]int // Rune index for each hard tab '\t' in lineBytes
-			//			var tabs      int // Length of lineTabs (number of hard tabs)
 			if t.UseHardTabs {
-				//				var ri int // rune index
-				//				var i int
-				//				for i < len(lineBytes) {
-				//					r, size := utf8.DecodeRune(lineBytes[i:])
-				//					if r == '\t' {
-				//						lineTabs[tabs] = ri
-				//						tabs++
-				//					}
-				//					i += size
-				//					ri++
-				//				}
 				lineBytes = bytes.ReplaceAll(lineBytes, []byte{'\t'}, tabBytes)
 			}
 
@@ -433,7 +433,6 @@ func (t *TextEdit) Draw(s tcell.Screen) {
 			col := t.x + columnWidth
 			var runeIdx int // Index into lineStr (as runes) we draw the next character at
 
-			// REWRITE OF SCROLL FUNC:
 			for runeIdx < t.scrollx && byteIdx < len(lineBytes) {
 				_, size := utf8.DecodeRune(lineBytes[byteIdx:]) // Respect UTF-8
 				byteIdx += size
@@ -543,7 +542,7 @@ func (t *TextEdit) Draw(s tcell.Screen) {
 			}
 		}
 
-		columnStr := fmt.Sprintf("%s%s", strings.Repeat(" ", columnWidth-len(lineNumStr)), lineNumStr) // Right align line number
+		columnStr := fmt.Sprintf("%s%s│", strings.Repeat(" ", columnWidth-len(lineNumStr)-1), lineNumStr) // Right align line number
 
 		DrawStr(s, t.x, lineY, columnStr, columnStyle) // Draw column
 	}
@@ -557,7 +556,7 @@ func (t *TextEdit) Draw(s tcell.Screen) {
 func (t *TextEdit) SetFocused(v bool) {
 	t.focused = v
 	if v {
-		t.SetLineCol(t.cury, t.curx)
+		t.updateTerminalCursor()
 	} else {
 		(*t.screen).HideCursor()
 	}

ui/theme.go

@@ -29,19 +29,17 @@ func (theme *Theme) GetOrDefault(key string) tcell.Style {
 
 // DefaultTheme uses only the first 16 colors present in most colored terminals.
 var DefaultTheme = Theme{
-	"Normal":           tcell.Style{}.Foreground(tcell.ColorSilver).Background(tcell.ColorBlack),
+	"Normal":              tcell.Style{}.Foreground(tcell.ColorSilver).Background(tcell.ColorBlack),
-	"Button":           tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorWhite),
+	"Button":              tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorSilver),
-	"InputField":       tcell.Style{}.Foreground(tcell.ColorSilver).Background(tcell.ColorBlack),
+	"InputField":          tcell.Style{}.Foreground(tcell.ColorSilver).Background(tcell.ColorBlack),
-	"MenuBar":          tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorSilver),
+	"MenuBar":             tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorDarkGray),
-	"MenuBarSelected":  tcell.Style{}.Foreground(tcell.ColorSilver).Background(tcell.ColorBlack),
+	"MenuBarFocused":      tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorLightGray),
-	"Menu":             tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorSilver),
+	"Menu":                tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorSilver),
-	"MenuSelected":     tcell.Style{}.Foreground(tcell.ColorSilver).Background(tcell.ColorBlack),
+	"MenuSelected":        tcell.Style{}.Foreground(tcell.ColorSilver).Background(tcell.ColorBlack),
-	"Tab":              tcell.Style{}.Foreground(tcell.ColorSilver).Background(tcell.ColorBlack),
+	"TabContainer":        tcell.Style{}.Foreground(tcell.ColorGray).Background(tcell.ColorBlack),
-	"TabContainer":     tcell.Style{}.Foreground(tcell.ColorSilver).Background(tcell.ColorBlack),
+	"TabContainerFocused": tcell.Style{}.Foreground(tcell.ColorSilver).Background(tcell.ColorBlack),
-	"TabSelected":      tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorSilver),
+	"TextEdit":            tcell.Style{}.Foreground(tcell.ColorSilver).Background(tcell.ColorBlack),
-	"TextEdit":         tcell.Style{}.Foreground(tcell.ColorSilver).Background(tcell.ColorBlack),
+	"TextEditSelected":    tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorSilver),
-	"TextEditColumn":   tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorGray),
+	"Window":              tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorDarkGray),
-	"TextEditSelected": tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorSilver),
+	"WindowHeader":        tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorSilver),
-	"Window":           tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorSilver),
-	"WindowHeader":     tcell.Style{}.Foreground(tcell.ColorBlack).Background(tcell.ColorWhite),
 }