Description of the new feature/enhancement

I tested using the Command Palette after finding how to bind it in the PR (perhaps adding an entry bound to null in defaults.json would be in order). First I enabled the AlwaysonTop Mode. Then I wanted to do another command from the Command Palette. But as soon as I enabled the AlwaysonTop Mode, the Command Palette exited. If I open it and then press ESC, it will close the Command Palette. So we have a way to exit without executing a command. Therefore from a usability point of view, please don't close it unless the user explicitly closes it using ESC (or any other bound key used for exiting). This would help someone open and close multiple tabs/panes quickly as well as enabling/disabling different visual modes quickly.

Proposed technical implementation details (optional)

Alter the method used for closing the Command Palette to require a user explicitly do so. We can add a setting to change this behavior (which I guess could also be toggable, inception anyone?) to always close after executing a command but I think not many users will want that behavior.