Fix TextView always visible scroll bar not appearing when empty

CHANGELOG

@@ -5,6 +5,7 @@ v1.5.6 (WIP)
 - Add CheckBox.SetCursorRune (cursors are now shown within CheckBoxes when focused by default)
 - Add DropDown.SetAlwaysDrawDropDownSymbol (DropDown symbols are now shown only when focused by default)
 - Add DropDown.SetDropDownOpenSymbolRune
+- Fix TextView always visible scroll bar not appearing when empty
 - Draw additional accents when rendering a list divider
 - Update Application.Draw and Application.QueueUpdateDraw to accept one or more
 primitives to draw instead of the whole screen

textview.go

@@ -1039,6 +1039,17 @@ func (t *TextView) Draw(screen tcell.Screen) {
 		t.regionInfos = nil
 	}
 
+	// Draw scroll bar last.
+	defer func() {
+		if !showVerticalScrollBar {
+			return
+		}
+		cursor := int(float64(len(t.index)) * (float64(t.lineOffset) / float64(len(t.index)-height)))
+		for printed := 0; printed < height; printed++ {
+			RenderScrollBar(screen, t.scrollBarVisibility, x+width, y+printed, height, len(t.index), cursor, printed, t.hasFocus, t.scrollBarColor)
+		}
+	}()
+
 	// If we don't have an index, there's nothing to draw.
 	if t.index == nil {
 		return
@@ -1252,14 +1263,6 @@ func (t *TextView) Draw(screen tcell.Screen) {
 		}
 	}
 
-	// Draw scroll bar.
-	if showVerticalScrollBar {
-		cursor := int(float64(len(t.index)) * (float64(t.lineOffset) / float64(len(t.index)-height)))
-		for printed := 0; printed < height; printed++ {
-			RenderScrollBar(screen, t.scrollBarVisibility, x+width, y+printed, height, len(t.index), cursor, printed, t.hasFocus, t.scrollBarColor)
-		}
-	}
-
 	// If this view is not scrollable, we'll purge the buffer of lines that have
 	// scrolled out of view.
 	if !t.scrollable && t.lineOffset > 0 {