There is sometimes a thin 'dead zone' strip across the editing window.

This bug is kind of hard to notice what is actually going on. The symptoms are that once in a while clicking the mouse on a line of code or clicking on a button in the editing (or debugging) edit window, nothing happens. Then clicking a few more times still nothing happens. Then moving the mouse a little, it works.

Having this happen a number of times, I one day noticed that the mouse pointer was an 'arrow' instead of an 'I-beam' while over editable text. On further investigation, I found that when this happens there is a thin horizontal strip all the way across the edit window where the mouse pointer will be an 'arrow'. This strip is narrower than a text line, so you can always click on the line by moving the mouse slightly up or down to get the 'I-beam' mouse pointer, then it will work. When I find this narrow 'dead strip', I notice that its position does not move even when the text is scrolled.

I just looked for it while writing this report and found it near the bottom edge of line 27 with my QtCreator full height on my 1920 x 1080 monitor, with the edit window also full height within QtCreator showing 46.5 lines of code, making it about 58% of the way down the edit window. I also measured the thickness of the strip at 4 pixels. I have usually found it in the lower part of the window, but sometimes a little higher or lower.

Now when I moved the border of the debugging window up to that position, the dead zone is still there though the mouse pointer is always an 'arrow' over the debugging control buttons, however if you look carefully, when the pointer is over a button, the button background turns a little lighter gray. But when the 'dead zone' is over the buttons, moving the mouse up and down on the button that background color changes so you can tell exactly where the 'dead zone' is. And when the pointer is on the 'dead zone' then clicking that button does nothing. Move the pointer up or down a bit and the button works as normal.

Then when I switched to the edit view (from debug view) the 'dead zone' disappeared - slowly moving my mouse from top to bottom, there was no 'arrow' 'dead zone' and switching back to debug view did not bring it back. But it will certainly be back soon enough.