Currently, the actions in the "Windows" menu (also available through the assigned hotkeys) add the sidebar/window when pressed, but to hide it, you have to click the "X" button at the top of the window with a mouse. The only exception is the "Core View" action, which works as a checkbox and toggles visibility of the core view.

In most software with similar layout (e.g. IDEs), pressing the same button/hotkey again hides the window, which lets you avoid using the mouse. I believe it would be more intuitive to make all the actions in the "Windows" menu work similarly to the "Core view" button, allowing the user to hide the window with the same action.