As a Roblox developer it is too difficult to insert/paste decals and textures in a controlled manner.
Studio automatically activates a “surface picker” mode when one of these instances is inserted, but this is extremely confusing and often interrupts workflow. There is no communication of this mode being enabled apart for the outline on part faces, which may not always be visible if the part you’re focusing is larger than the viewport or too far away, and there is no way to cancel out of this mode other than to explicitly select a face on a part.
If you’re looking in the explorer and you’re lucky enough to be looking at the parts nearby the camera, all you see is your decal instance flying around between them as you move your mouse around.
For example, if I’m trying to insert a decal into an instance in my game from the toolbox or insert object widget, I am forced into this surface picker mode.
If I’m working on a part, I need to make sure I can click on it to apply the decal, which isn’t always possible if it’s embedded into the world and cluttered with other parts, or is too small. I just want to put this decal into the part I have selected and set the face via the properties panel.
However, if I want this decal under another instance for storage purposes (e.g. under a script), I have to first click on a part somewhere to get out of this surface picker mode so I can then drag and drop the decal into the instance I want it under. I can’t just cut and paste it either since that puts you in the surface picker mode, so I need to traverse the entire explorer tree to do this.
To solve these UX problems, the mouse cursor should change to an icon suggesting Studio is in “surface picker” mode. This would eliminate the confusion since there is no other feedback to the user when entering this mode.
Maybe something like this: 
It should also be possible to cancel out of this mode by pressing ESC (which is the hotkey to clear the selection), perhaps additionally by pressing right click since this also feels natural. It doesn’t make any sense to press ESC to clear your selection, but still be stuck in this mode. The decal should just be left at its default properties / pasted properties when canceling the surface picker.