Bug 25690 – Drop event is never fired when dragover's target element is removed even if the event was canceled by its ancestor

• Component: UI Events
• Status: NEW

[noel gordon]

Create a <div> with text inside it, attach drag drop listeners.  Dynamically update the <div> text (using .innerHTML, for example) while dragging Text or URLs over the <div>.

1) Release the mouse button while dragging over the dynamic text; a drop event should be generated.

2) Press the escape key (to cancel the drag) while dragging over the dynamic text; a dragleave event should be generated.

Safari 4 Beta (5528.16), FAILS
 1) mouse button release: no drop event is generated.  
 2) escape key: no dragleave event is generated.

Safari 3.1.2 (5525.2.0.1), FAILS
 1) mouse button release: no drop event is generated.  
 2) escape key: no dragleave event is generated.

IE7 (7.0.60001.18000) Vista SP1, OK
 1) mouse button release: drop event generated.  
 2) escape key: dragleave event generated.

IE6 (6.0.2900.5512.xpsp_sp3) XP SP3, OK
 1) mouse button release: drop event generated.  
 2) escape key: dragleave event generated.

[noel gordon]

Created attachment 30187 [details]
Drag Drop Test Case

[noel gordon]

Comment on attachment 30187 [details]
Drag Drop Test Case

Try dropping on events count numbers.

[Mark Rowe (bdash)]

*** Bug 25691 has been marked as a duplicate of this bug. ***

[Julie Parent]

Adding arv, who is working on another drag/drop fix that seems to fix this too.

[Ryosuke Niwa]

It seems like this bug has been fixed?

[noel gordon]

Nope.  Load test case in Tools/Scripts/run-safari --release  and drop on the moving numbers, screenshot attached.

[noel gordon]

Created attachment 186295 [details]
Drop on the moving numbers, no drop event results

[Ryosuke Niwa]

(In reply to comment #7)
> Created an attachment (id=186295) [details]
> Drop on the moving numbers, no drop event results

How do we know it's failing?

[noel gordon]

No drop event.

[Ryosuke Niwa]

(In reply to comment #9)
> No drop event.

drag_drop_count says 7.

[noel gordon]

That was from tests where I dropped the data _not_ on from the moving text.

[Ryosuke Niwa]

(In reply to comment #11)
> That was from tests where I dropped the data _not_ on from the moving text.

I'm not sure what the bug is then. Could you please create a better reduction where it can clearly show PASS or FAIL? All the description on this bug so far has been extremely vague.

[noel gordon]

Drop text in the blue box: a drop event is generated, except if you drop on the updating text, like the numbers shown for drag_event_count for example.

Expected: a drop event should be generated no matter where you drop in the blue box.

[Ryosuke Niwa]

Created attachment 186308 [details]
Reduction

Thanks for the clarification.

[Radar WebKit Bug Importer]

<rdar://problem/13142049>

[noel gordon]

(In reply to comment #14)
> 
> Thanks for the clarification.

Thanks for the reduction.  Minor nit.

  <div ondragover="event.dataTransfer.dropEvent='copy';return false"
          ondrop="alert('PASS');" ondragenter="this.innerHTML+='|';">

ondragenter should also return false.

[Ryosuke Niwa]

(In reply to comment #16)
> (In reply to comment #14)
> > 
> > Thanks for the clarification.
> 
> Thanks for the reduction.  Minor nit.
> 
>   <div ondragover="event.dataTransfer.dropEvent='copy';return false"
>           ondrop="alert('PASS');" ondragenter="this.innerHTML+='|';">
> 
> ondragenter should also return false.

Not in WebKit.

[noel gordon]

(In reply to comment #17)

> > ondragenter should also return false.
> 
> Not in WebKit.

Really?  It's required by HTML5.  The standard _does not_ say that a dragenter event must be followed by a dragover event, but it does say that their default actions must be cancelled to permit a subsequent drop event.

So the event sequence dragenter -> {dragleave|drop} is permitted per spec, but the drop should be generated only if the default action of dragenter event was cancelled.

[Daniel Cheng]

(In reply to comment #18)
> (In reply to comment #17)
> 
> > > ondragenter should also return false.
> > 
> > Not in WebKit.
> 
> Really?  It's required by HTML5.  The standard _does not_ say that a dragenter event must be followed by a dragover event, but it does say that their default actions must be cancelled to permit a subsequent drop event.
> 
> So the event sequence dragenter -> {dragleave|drop} is permitted per spec, but the drop should be generated only if the default action of dragenter event was cancelled.

I've spent a considerable amount of time trying to get the D&D event handling to follow the HTML spec (especially wrt cancelling the dragenter/dragover events), and it's rather tricky (often times, it only fails for one specific type of element).

I'll try to take a look at this in the next few weeks, but I have quite a lot of other things on my plate atm.