As you probably know, you can easily hide and un-hide lightroom panels.
It can be done with the keyboard using the TAB key or by clicking on the triangle on external actuators.
Lightroom provides a nice enhancement in order to customize the trigger for panels appearance when hidden.
The default is to automatically hide and show based on mouse hover.
This can be customized by simply right clicking on one of the external actuators.
Once clicked a new menu is presented with several options:
The options are quite straight forward so once you’re familiar with the menu the rest is simply playing with the options until you find the one which best suits your needs.