Draggable Text Example - Possible to drag the text under the window's top border

Description:

It is possible to drag the text under the window's top border. It is then not possible to recover the text that was dragged there, maximizing the window will not help.
Steps to reproduce:

1. Open the  Draggable Text Example
2. Drag some of the text exactly under the top border of the window.
3. Maximize the window.
4. The text that was dragged cannot be found anywhere

Expected behavior:

It should not be possible to drag the text under the window's top border or it should be possible to recover the text that was dragged there.
Observed behavior:

Dragging text under the window's top border result in losing it.
Special notes: