resolve a couple thumbnail-padding issues
no fade-in when doing in-scale thumbnail
resolve a small visual glitch

The right-most item was slightly cut off on the
right -hand side when there were separators.
always show the app switcher, even when there are no items to display
bring back something resembling the old 'icons+previews' style, keeping the new style under another name
small adjustment to thumbnail-size calculation
all thumbnails should have the same scale also in inline-thumbnails mode
take thumbnail border into account when calculating thumbnail size