Add a little icon, similar to the 'this slide has a slide transition', to the slide thumbnails in the Impress slidesorter. Thusly, users can visually discern slides that show differently initially than in edit view.
Relevant code: PageObjectPainter::PaintTransitionEffect() in sd/source/ui/slidesorter/view/SlsPageObjectPainter.cxx, just reuse that for the custom animation, and put it at the opposite side of the thumbnail. Instead of getTransitionType(), call getMainSequence() on the page.
Ciorba Edmond committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/core/commit/?id=e5990a9dcd97c2231115eae83770f9e6e7e130e9 fdo#65456 - Provide visual clues in slidesorter for custom animation. The patch should be included in the daily builds available at http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: http://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.
Migrating Whiteboard tags to Keywords: (EasyHack DifficultyBeginner SkillCpp ) [NinjaEdit]