Overlay messages cropped by side panes
Overlay messages (lua: `darktable.print`) are cut off by the side
panes in Lighttable and Darkroom mode.
Verify: Write a lua script that produces a lengthy message, like the
first shortcut example in the manual. The overlay will lie over the
middle pane, but be obscured by the panes on the right/left where
extending over the middle pane.