Pop-up menu is a small context-sensitive menu with handy commands and options applicable in the current working mode. Pop-up menu is hidden and it appears only when you invoke it.
On devices with mouse the pop-up menus appear upon click of secondary mouse button.
There is a number of pop-up menu buttons in Studio's windows and panels. They are intended mostly for use witch touch screen on devices without a mouse, but they can be used with mouse too if you preffer a single-button work.