QLineEdit gives away to Qt's shortcut system some key events (basically, everything with modiiers) even if it could handle them and use for text editing, when there is registered shortcut, matching this key input.
Example: pressing "ctrl+backspace" (used on my machine to delete word left from cursor) in layer name editing field will cause filing canvas with background color, instead of deleting word left from cursor.
This patch fixes that without replacing QLineEdits all over the application.
Also, now pressing tab and backTab when editing layer's name will switch you to editing next/previous layer's name, even if there is shorcut assigned to tab and backtab.