Drag-n-drop to an application is erroneously handled as "move"

My problem: drag-n-dropping to a specific Windows app – Directory Opus – is handled as a "move" operation, despite the (target) app itself seemingly communicating about the drag operation appropriately.

I researched a bit on this now (also in forums here) and I suspect that the issue is with WinSCP or more specifically – without knowing much about Win32 development – how it handles DnD or maybe how takes signs from the target app.

I tested quite a few apps as to how they handle DnD with DOpus being the target:

• Windows Explorer: as expected
  
• Total Commander: as expected
  
• Nexus File: always moves
  
• WinSCP: always moves
  
• AIMP: as expected (from playlist)
  
• foobar2000: always moves (from playlist)
  
• FileZilla: always copies
  

The pattern seems to be that there is a possible miscommunication with only some apps, as others seem to be behaving appropriately (including Windows Explorer). Can anything be done here? Would it be possible to disclose how DnD is handled within WinSCP so I could relay it with DOpus developers?

For a start, please see Drag & Drop moves instead of copying..

Awesome, thanks, this solves it completely. As a sidenote, it would be cool to have this as a GUI option – novice users may have a hard time setting raw config/ini files, and this is a case where data can be easily lost unintentionally.

The option is needed very rarely. Only then you are dragging files to an application that does not support CF_PREFERREDDROPEFFECT.

As per the above post, sadly this could mean many popular applications. The user will never know when he's dropping to such an app. Having a checkbox with a label like "Never move files on drag&drop, regardless of target application preference" would mean some easy safety from this.