I have the same issue. I have learnt to press the Return key to quickly exit the tool I am in, but there are many times I’d like to simply click the tool to review the changes it made and then click away from it again (as mentioned by Platypus in the first post).
For example, using the ‘Local Adjustments’ button the check the position of the control points in an image.
Click on ‘Local Adjustments’
View the Control Points you have created
Now, currently to leave the Local Adjustments UI, one needs to either move the mouse to the opposite edge of the displayed image (top of image to the bottom) to click on the ‘Close’ button, or move a hand on the keyboard and press the "Return’ key.
The proposal is that the User would be able to simply click the ‘Local Adjustments’ button again to close the UI.
I have to admit, when I first started using PL 18months ago that is exactly what I did to try and close the UI.