Those who experienced the "GNOME hot corner problem" typically did so right away in the first exercise when attempting to use the program menus. While testers were able to recover from the hot corner, it definitely caused disruption several times throughout the test.
None of the users in the usability test had used GNOME, so they did not have previous experience in using GNOME. The programs they were evaluating in the usability test were running "maximized" so when they needed to use the program menus (say, the "File" menu) they would naturally bring the mouse towards the upper left corner of the screen ... and then "overshoot" the menu, activating the hot corner. Suddenly, the screen changed completely - all the program windows from the test were represented as smaller "tiles" on the screen.
Most of these users (5 of the 6 testers) recognized that they needed to click on the "tile" for the program they were in, to bring up the program again. But in doing so, I heard these quotes from the testers:
- "Hey, what happened."
I think the quotes represent confusion and surprise at the hot corner. Testers frequently experienced the "hot corner problem" multiple times throughout the entire usability test. I am not sure why 1 tester happened never to hit the hot corner during the entire test.
I'll add that a GNOME extension, "No Topleft Hot Corner," disables this hot corner behavior. However, users would have to know to seek out and install this add-on, as it is not available by default.