In this post I want to explain a little-known (at least to me) feature of the Ipe drawing editor: you can use a so-called clipping path to restrict the drawing of an object to a certain arbitrarily-shaped area.
This is an interesting trick that I noticed if you are running KWin: you can very easily forcefully quit a program. Press Ctrl + Alt + Esc, and the cursor is replaced by a skull. Then click the program you want to kill, and it is gone immediately. If you accidentally pressed the shortcut and you don’t want to kill any program, just click on the right mouse button to dismiss the function.