Extended WPF Toolkit™ Community Edition MultiLineTextEditor
The free Community Edition of the Exceed MultiLineTextEditor lets you display a small textbox with a letter A icon with a dropdown arrow. This text editor lets you save on screen real estate by hiding away the actual multi-line text. The multi-line text will
only display when you click the dropdown to reveal the editing box.
.AddAnything<MultiLineTextEditor, Grid>(10, 3)
If screen real estate is not an issue, and so you just need a regular textbox with multi-line text and a scrollbar, you may use the regular WPF TextBox initialized for ScrollViewer support (to allow accessing the Scrollbar which may then have its colors modified
by the ApplyToScrollViewer method.)
#region Setup Multi-Line TextBox with styled ScrollViewer
TextBox trex = new TextBox();
trex.InitializeForScrollViewerSupport(100D, 150D, 140D); //TextBox is NOT an IParent but it is an IScrollViewerStrategy.
ScrollViewerStyle.ApplyToScrollViewer<TextBox>(trex, "PowderBlue", "White", "Blue");
trex.Text = "This is an example\n of a\n multi-line textbox with enough text in it to trigger the vertical scrollbar to display.";