change: added option to span selection highlight across width of list view

list.go

@@ -47,6 +47,9 @@ type List struct {
 	// If true, the selection is only shown when the list has focus.
 	selectedFocusOnly bool
 
+	// If true, the selected background color spans the entire view.
+	spanSelectionHighlight bool
+
 	// An optional function which is called when the user has navigated to a list
 	// item.
 	changed func(index int, mainText, secondaryText string, shortcut rune)
@@ -139,6 +142,15 @@ func (l *List) SetSelectedFocusOnly(focusOnly bool) *List {
 	return l
 }
 
+// SetSpanSelectedBackgroundColor sets a flag which determines whether the
+// colored background of selected items spans the entire width of the view. If
+// set to true, the highlight spans the entire view. If set to false, only the
+// text of the selected item from beginning to end is highlighted.
+func (l *List) SetSpanSelectedBackgroundColor(span bool) *List {
+	l.spanSelectionHighlight = span
+	return l
+}
+
 // ShowSecondaryText determines whether or not to show secondary item texts.
 func (l *List) ShowSecondaryText(show bool) *List {
 	l.showSecondaryText = show
@@ -275,8 +287,16 @@ func (l *List) Draw(screen tcell.Screen) {
 
 		// Background color of selected text.
 		if index == l.currentItem && (!l.selectedFocusOnly || l.HasFocus()) {
-			textWidth := StringWidth(item.MainText)
-			for bx := 0; bx < textWidth && bx < width; bx++ {
+
+			// Width of background color of selected item.
+			var textWidth int = width
+			if !l.spanSelectionHighlight {
+				if w := StringWidth(item.MainText); w < textWidth {
+					textWidth = w
+				}
+			}
+
+			for bx := 0; bx < textWidth; bx++ {
 				m, c, style, _ := screen.GetContent(x+bx, y)
 				fg, _, _ := style.Decompose()
 				if fg == l.mainTextColor {