Automatically Return to Previous Tab on File Selection

Pass tab name to inputs on configuration editor tabs, so file input
view can pass it as default `returnToTab` option to file selection
handler.
Rework Image Positioning Dialog
Merge pull request #211 from tf/auto-return-to-tab

Automatically Return to Previous Tab on File Selection
Merge pull request #212 from tf/new-background-positioning

Rework Image Positioning Dialog