I updated roundcube from 0.9 to 1.2.3 and since then I do have problems wirh drag & drop. I try to describe:
When I select a message the message is shown. When I now click once onto this message in the message list then roundcube believes that I want to drag that message, means the message "moves with my mouse cursor", it sticks with my mouse cursor. Always. Sometimes this also happens when I select a message for the first time.
When working with message filters (sieve), I am not able to drag filters and re-position them. I can select the filter, again it sticks even when I release the mouse and when I try to drop the message nothing happens, the item magically moves back, that's it. The small arrows in filters do not work, too.
I changed the skins. I changed the browsers (IE / Chrome). I changed the mouse driver from MS mouse to Synaptics and back again. Nothing helped. What I did not try is another OS as I currently have access to Windows 10 only.
Version 0.9 worked like a charm. It does these strange things since I updated to 1.2.3.