Fixes #1930. Trailing whitespace makes MessageBox.Query buttons disappear. (#1931)

Co-authored-by: Tig Kindel <[email protected]>

Terminal.Gui/Windows/MessageBox.cs

@@ -242,7 +242,7 @@ namespace Terminal.Gui {
 			const int defaultWidth = 50;
 			int textWidth = TextFormatter.MaxWidth (message, width == 0 ? defaultWidth : width);
 			int textHeight = TextFormatter.MaxLines (message, textWidth); // message.Count (ustring.Make ('\n')) + 1;
-			int msgboxHeight = Math.Max (1, textHeight) + 3; // textHeight + (top + top padding + buttons + bottom)
+			int msgboxHeight = Math.Max (1, textHeight) + 4; // textHeight + (top + top padding + buttons + bottom)
 
 			// Create button array for Dialog
 			int count = 0;