You can use it in the viewer mode now, but rotation is a slow operation and there is no progress bar.

It is unclear if anything is happening for a second or two, while the rotation is being calculated.

A progress bar or a waiting-cursor would be heplful.

- Mike

Hmm, there is a progress bar after all. But it takes too long to first appear.

- Mike

the progress dialog is shown after a second, 
the value is in gthumb/gth-progress-dialog.c (SHOW_DELAY) 

maybe half a second is enough?

That helps in the viewer mode.

The browser mode stills feels awkward, probably because the progress bar disappears before the thumbnail is regenerated, and it takes a second or two to generate the thumbnail.

Maybe a waiting cursor should be shown while the selected image is being rethumbnailed?

- Mike

When the thumbnail generation starts the thumbnail should be substituted with the "image-loading" icon.  
In theory this should already work, but for some reason it doesn't.  I need to investigate.

Changed version from 2.11 to 2.13. Progress bar is still odd.

- Mike

fixed in current master with commit 5bb2f8aff9409e86de7beb1491dfee23e16b67fb