Need to call baseclass AttachedToWindow()
Set tooltip in instance of close button, not class.

Also set a similar tooltip for the previous and next buttons and
comments for translators.
Allow Magnify to resize to smaller sizes more gracefully.

Fixes ticket #4146

Signed-off-by: Matt Madia <mattmadia@gmail.com>
Automatic whitespace cleanup. No functional change.
Style fixes from #4146 comment:11.