Most actions triggered by mouse events on the title bar of a window can also be performed on the contents of the window (i.e. not the titlebar) by holding down Alt (or whatever modifier has been configured). Examples:

- Focusing: Left click on titlebar == Alt + left click on window
- Window menu: Right click on titlebar == Alt + right click on window
- Moving: Left drag on titlebar == Alt + left drag on window

Now, a window can be sent to the back by middle clicking on its titlebar. However, Alt + middle click on a window does not send it to the back. It should!

Note that Alt + middle drag is used to resize a window. Suggestion: when the (x,y) position of the pointer do not change between mouse button press and mouse button release, it should be treated as a "send window to back" command.