open_window has a better API than open_standard_window. It uses named
parameters and supplies default values for everything you don’t specify. This
way, you can use every feature which X11::XCB::Window supports.
This fixes ticket #100, and is best explained using a little example.
Consider the following layout:
+---+---+
| | X |
+---+---+
| X |
+---+---+
Where X marks a window, so you have an empty container in the upper
left, the container on the bottom is snapped to the right. Before
this commit, nothing would happen when focusing "above". After
this commit, the upper window gets focused.
