Thank you for the suggestions and help, it got me going in the right direction.
The issue was embarrassingly easy, and was not related to Qt or VisualGDB…
The script that was starting my VisualGDB app was running startx with the “-nocursor” option, because it’s on a touch-screen device, and I wanted to hide the mouse cursor. As it turns out, that entirely eliminates the cursor, including in text boxes.
I changed the script to instead use “unclutter -idle 0” instead, and everything is fixed. *sigh*
I am glad to know about SmarTTY and the VisualGDB Diagnostic Console, those have both been useful already. Thank you!