Editor closes when selecting text

[PVince81]

Steps:

1. Open text editor
2. Type in a row of text
3. With the mouse, hold left button down around the end of the sentence and drag the mouse to the left to select the text. Continue moving and exist the text editor window and release the button there.

Expected

Text is selected, editor remains.

Actual

Editor closes.
Bug is likely that there's a mouseup event outside the text editor window. That one must be blocked when dragging or selecting text.