This is a Windows specific issue. On linux, slideshow clips using mime type are created with an url like :
(will take all jpg images in the Pictures folder
But on Windows, the url needs to be:
So we need to adjust the code to append a backslash to the path (and adjust a few places where we check for ".all." to identify mime slideshows.
in line 423 of src/project/dialogs/slideshowclip.cpp should allow the creation of slideshow clips
see Bug 379351