Created attachment 107298 [details] open-close-popup-panel-button If 'Tree' panel is in the default position and 'Move popup panel clockwise' button wasn't clicked - create breakpoint when changing vertical size of the popup 'Tree' panel by dragging it to the bottom of a panel. There is a breakpoint at the top of a panel but there is not breakpoint at the bottom. There may be situation when user reduces height of the popup 'Tree' panel by dragging to the very bottom of a panel. In this case pressing of 'Open/Close the popup panel' button will not change almost anything visually on a panel. Also after breakpoint triggers 'Close the popup panel' button can transform into 'Open the popup panel' button.
Doesn't seem very important to me.