This thing was great at first. For example, I comment a group of highlighted code by hitting the slash and the "What happened" dialog pops up and tells me what happened.
Now it is just freaking annoying. I only really needed to know what happened the first time. Is there any way to disable this thing?
The pop-ups only appear the first few times you do something to ensure you are clear what's been done, after that they stop appearing. I think you might be able to change that behaviour from the DevExpress menu.
The "What happened?" dialog can be disabled from the options screen.
Use either the [CTRL+SHIFT+ALT+O] key combination or the DevExpress\Options menu to reach the options screen.
Then navigate the tree on the left to the Core\Features
The option you're looking for is the first checkbox on this screen.
If you untick "Show Feature UI window", then this dialog will not show again.
If you click the "OK" or "Disable" link in the "What happened?" hint - it won't appear for the specific feature anymore (it will remember your choice for this specific feature), but will appear for others only.