To raise a partially concealed window to the top of the window stack, or in other words to the front of the display, position the pointer on the window's frame and click Button 1. Be sure that the pointer is not resting on one of the window frame command buttons: minimize, maximize, or window menu.
The window manager also provides default methods for raising a window from the keyboard:
When you are using an explicit input focus policy, raising a window to the top of the stack also sets the input focus to that window.
If you are using a pointer focus policy, however, the window manager does not automatically set input focus to the raised window. In other words, a window can continue to receive input even though it is not at the top of the stack.
You can, however, set a resource in the X configuration file to move a window automatically to the top of the stack when you set input focus to that window (see Setting input focus policy).