List (and therefore also DropDown) will scroll if currently selected item is not on screen anymore. Fixes #71

dropdown.go

@@ -254,8 +254,14 @@ func (d *DropDown) Draw(screen tcell.Screen) {
 		lwidth := maxWidth
 		lheight := len(d.options)
 		_, sheight := screen.Size()
-		if ly+lheight >= sheight && ly-lheight-1 >= 0 {
+		if ly+lheight >= sheight && ly-2 > lheight-ly {
 			ly = y - lheight
+			if ly < 0 {
+				ly = 0
+			}
+		}
+		if ly+lheight >= sheight {
+			lheight = sheight - ly
 		}
 		d.list.SetRect(lx, ly, lwidth, lheight)
 		d.list.Draw(screen)

list.go

@@ -193,8 +193,24 @@ func (l *List) Draw(screen tcell.Screen) {
 		}
 	}
 
+	// We want to keep the current selection in view. What is our offset?
+	var offset int
+	if l.showSecondaryText {
+		if l.currentItem >= height/2 {
+			offset = l.currentItem + 1 - (height / 2)
+		}
+	} else {
+		if l.currentItem >= height {
+			offset = l.currentItem + 1 - height
+		}
+	}
+
 	// Draw the list items.
 	for index, item := range l.items {
+		if index < offset {
+			continue
+		}
+
 		if y >= bottomLimit {
 			break
 		}