Add tabbar.active color group (#1831)

Added tabbar.active color group for displaying the name of the active
tab in the tabbar with different colors.

If tabbar.active is not defined in the colorscheme, the active tab name
is displayed with the same colors as inactive ones.

Ref #1646

internal/display/tabwindow.go

@@ -98,8 +98,16 @@ func (w *TabWindow) Display() {
 	if style, ok := config.Colorscheme["tabbar"]; ok {
 		tabBarStyle = style
 	}
+	tabBarActiveStyle := tabBarStyle
+	if style, ok := config.Colorscheme["tabbar.active"]; ok {
+		tabBarActiveStyle = style
+	}
 
-	draw := func(r rune, n int) {
+	draw := func(r rune, n int, active bool) {
+		style := tabBarStyle
+		if active {
+			style = tabBarActiveStyle
+		}
 		for i := 0; i < n; i++ {
 			rw := runewidth.RuneWidth(r)
 			for j := 0; j < rw; j++ {
@@ -114,7 +122,7 @@ func (w *TabWindow) Display() {
 				} else if x == 0 && w.hscroll > 0 {
 					screen.SetContent(0, w.Y, '<', nil, tabBarStyle)
 				} else if x >= 0 && x < w.Width {
-					screen.SetContent(x, w.Y, c, nil, tabBarStyle)
+					screen.SetContent(x, w.Y, c, nil, style)
 				}
 				x++
 			}
@@ -123,21 +131,21 @@ func (w *TabWindow) Display() {
 
 	for i, n := range w.Names {
 		if i == w.active {
-			draw('[', 1)
+			draw('[', 1, true)
 		} else {
-			draw(' ', 1)
+			draw(' ', 1, false)
 		}
 		for _, c := range n {
-			draw(c, 1)
+			draw(c, 1, i == w.active)
 		}
 		if i == len(w.Names)-1 {
 			done = true
 		}
 		if i == w.active {
-			draw(']', 1)
-			draw(' ', 2)
+			draw(']', 1, true)
+			draw(' ', 2, true)
 		} else {
-			draw(' ', 3)
+			draw(' ', 3, false)
 		}
 		if x >= w.Width {
 			break
@@ -145,6 +153,6 @@ func (w *TabWindow) Display() {
 	}
 
 	if x < w.Width {
-		draw(' ', w.Width-x)
+		draw(' ', w.Width-x, false)
 	}
 }