Version: unspecified (using KDE 4.5.95)
It seems like in KDE 4.6 you cannot drag files from e.g. Dolphin onto a taskbar entry, e.g. another dolphin window, or VLC, and then drop the file into that application.
The window of the taskbar entry simply does not “pop up”, like it did in previous KDE versions.
Reported at bug 261443. Merging.
*** This bug has been marked as a duplicate of bug 261443 ***