I think there is an inconsistency between thunar and the desktop. Expectation: If I drag a file/folder and hover this item over a folder, the folder should be highlighted or show some kind of visual feedback. Thunar react that way and even put a rectangle around the possible target. Current behavior: Even if dragged file/folder are hovering over a folder, the folder is not highlighted. If you hover the mouse only, it does highlight it though. Observed in: I saw this behavior on 4.12 and tried on older VM that contained 4.8 and they reacted the same. It seems to be by design. Reason for this enhancement: Visual feedback are important to know if an action will occur or not when dragging a file. Most desktop environment usually have this kind of behavior on the desktop so I was surprised that it was not the case for XFCE. When I was positioning manually my files/folders on the desktop, they were vanishing and I didn't know why until I realised that I was hovering near a folder by accident and found those items were moved there.
The code for this was removed due to causing glitches (https://bugzilla.xfce.org/show_bug.cgi?id=10450).
Created attachment 8516 wip patch Here is a patch which is based on the removed code. It is an attempt to restore the visual feedback (a frame around the icon cell) when dragging an item. Additionally, I added the mentioned hover highlight.
The patch looks good, I didn't notice the glitch which caused this feature to be removed, congratulations. I would just get rid of that frame because it's ugly (IMHO) and Bug 11094. What do you think? Thanks.
Nice catch! I as well would vote for dropping the frame. (Though I dont know how it is related to Bug #11094)
Theo Linkspfeifer referenced this bugreport in commit 26252ee801e4fe5d73ea9dcdd8f68351b320a3b5 Highlight drag target when hovering it (Bug #12695) https://git.xfce.org/xfce/xfdesktop/commit?id=26252ee801e4fe5d73ea9dcdd8f68351b320a3b5