The CaptionHeight property of ToolWindow determines the height of the area where you can start dragging the window, starting from the top edge of the window. Currently, ToolWindow is using a fixed height based on the default title's content. However, the Title and TitleTemplate properties allow you to introduce a title with bigger height. In this case, if the title height is bigger than the default CaptionHeight, you cannot start dragging if the mouse is under the CaptionHeight's position.

Adjust the CaptionHeight dynamically, according to the actual title content height.