Fast Panorama preview: regroup checkboxes and image numbers in "displayed images" section

[zarl]

The Fast Panorama preview window has a "displayed images" section in all tabs which looks like this:

[All] [None] [x] 0 [x] 1 [x] 2

So now image numbers are centered between two checkboxes (or was it one checkbox between two image numbers? This makes me feel dizzy...) which can puzzle new users and still me, too. Also projects containing a larger number of photos will soon show a horizontal scroll line which makes managing those images cumbersome.

I will now focus on the Move/Drag tab since this even needs to show two rows of checkboxes if one of the "single" drag modes is selected. The following examples show how I think this section could be organized in a better way: please group (one or two, depending on the drag mode) checkboxes and their respective image number in one column like this:

 show | Image #: 0 1 2 3 4
[All ] | display: [x] [x] [x] [x] [x]
[None] | move: [x] [x] [x] [x] [x]

Now a much larger number of images can be shown in one row without the need of scrolling horizontally.

Please notice my two informative labels 'display:' and 'move:' (or drag?) left of the checkboxes of image 0 (only needed if drag mode is enabled).

This can be even thought further:
If the user selects "Group by: Stacks" in Photos tab -> switch "displayed images" section to show stack numbers instead of image numbers to further reduce the amount of checkboxes in this area:

 show | Stack #: S0 S1 S2 S3 S4
[All ] | display: [x] [x] [x] [x] [x]
[None] | move: [x] [x] [x] [x] [x]

Here I changed the row description ("Stack #:" is shown instead of "Image #:") and also added a 'S' to make clear that these are stack numbers instead of image numbers.

[tmodes (tmodes)]

The checkboxes were only used on Mac, Windows and GTK+ are using toggle buttons (for historic reason, older wxWidgets version did not support these controls on Mac). The toggle buttons are now with wxWidgets 3.x also supported on Mac. So I removed the checkboxes on Mac. This should reduce the confusion.