343268 - DnD month view: Uncaught exception if Drag and Drop is aborted with Escape key

Status: VERIFIED FIXED

(Calendar :: Internal Components, defect)

Description

[Stefan Sitter [:ssitter]]

Fall out from Bug 312736:
DnD month view: Uncaught exception if Drag and Drop is aborted with Escape key

Steps to Reproduce:
1. Switch to Month view
2. Create event
3. Drag event and abort Drag and Drop operation by pressing the Escape key

Actual Results:
Drop shadow is displayed on last position. Event is not displayed. After refresh of view the event is displayed again but Drag and Drop is not possible anymore. JavaScript console shows:

Error: uncaught exception: [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIDragService.invokeDragSession]"  nsresult: "0x80004005 (NS_ERROR_FAILURE)"  location: "JS frame :: chrome://calendar/content/calendar-month-view.xml :: onxbldraggesture :: line 164"  data: no]

Expected Results:
Drag and Drop operation is aborted gracefully.

Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.9a1) Gecko/20060630 Sunbird/0.3a2+

Comment 1

[Joey Minta]

This is WFM, although I can see code in nsDragAndDrop.js related to it.  Is this platform specific?

Comment 2

[Stefan Sitter [:ssitter]]

(In reply to comment #1)
Using Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9a1) Gecko/20060630 Sunbird/0.3a2+ I don't see the exception but the other steps listed above in 'Actual Results'. (But that steps apply to almost every DnD problem reported.)

Using Thunderbird 1.5.0.4 (20060516) and Lightning 0.1+ (20060630) on Windows shows the same exception.

Comment 3

[Joey Minta]

http://lxr.mozilla.org/seamonkey/source/toolkit/content/nsDragAndDrop.js#429

Comment 4

[Reed Loden [:reed]]

The bugspam monkeys have struck again. They are currently chewing on default assignees for Calendar. Be afraid for your sanity!

Comment 5

[Joey Minta]

When the patch in bug 343190 lands, we're going need to do more here than just catch().

Comment 6

[Stefan Sitter [:ssitter]]

Retest with Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.9a2pre) Gecko/20070112 Calendar/0.4a1:

Aborting Drag and Drop operation by pressing the Escape key still results in the error message shown in Comment #0.

But: After that the event is now displayed on original date. Further Drag and Drop operation is possible. This was probably fixed by checkin for Bug 343190.

Comment 7

[Stefan Sitter [:ssitter]]

Retest with Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1b3pre) Gecko/20081219 Calendar/1.0pre (BuildID: 20081219033507)

Aborting Drag and Drop operation by pressing the Escape key still results in the same error message but new location:

Error: Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIDragService.invokeDragSession]
Source file: chrome://calendar/content/calendar-dnd-listener.js
Line: 571

Afterwards the drop shadow is still displayed in the view. But event is displayed on original date. Further Drag and Drop operation is possible.

Comment 8

[Philipp Kewisch [:Fallen][📱📆]]

Attachment: Fix - v1

I found no exception, but a warning. This patch gets rid of the warning.

Comment 9

[Stefan Sitter [:ssitter]]

I can still reproduce using Lightning 1.0pre (BuildID: 20090316031544) with Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1b4pre) Gecko/20090316 Shredder/3.0b3pre:

[[[
Error: uncaught exception: [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIDragService.invokeDragSession]"  nsresult: "0x80004005 (NS_ERROR_FAILURE)"  location: "JS frame :: chrome://calendar/content/calendar-dnd-listener.js :: invokeEventDragSession :: line 630"  data: no]
]]]

Maybe different drag'n'drop behavior Windows vs. Linux?

Comment 10

[Stefan Sitter [:ssitter]]

Comment on attachment 367571 [details] [diff] [review]
Fix - v1

What warning did you saw? 
Maybe |return false| should be just |return;|? The same check is used in dragenter/dragdrop and I'd like to keep them similar if possible.

Comment 11

[Philipp Kewisch [:Fallen][📱📆]]

Warning: function onxbldragover does not always return a value
Source File: chrome://calendar/content/widgets/calendar-widgets.xml
Line: 375, Column: 31
Source Code:


This is the warning, it shows up when dragging in the month view. For multiday view right now I can't seem to cancel the drag at all!?

Comment 12

[Stefan Sitter [:ssitter]]

Comment on attachment 367571 [details] [diff] [review]
Fix - v1

I'd keep the if clause as used in dragover, dragenter and dragdrop handler but change |return false;| to just |return;|

Comment 13

[Philipp Kewisch [:Fallen][📱📆]]

Attachment: [checked in] Fix warning - v2

Like so?

Comment 14

[Stefan Sitter [:ssitter]]

Comment on attachment 371065 [details] [diff] [review]
[checked in] Fix warning - v2

I guess this should work r=ssitter

Comment 15

[Philipp Kewisch [:Fallen][📱📆]]

Pushed to comm-central <http://hg.mozilla.org/comm-central/rev/b08051438f9f>

-> FIXED

Comment 16

[Stefan Sitter [:ssitter]]

Reopening because the patch fixes only the warning but not the exception.

Lightning/1.0pre (BuildID: 20090408054113) with Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1b4pre) Gecko/20090408 Shredder/3.0b3pre:

Error: uncaught exception: [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIDragService.invokeDragSession]"  nsresult: "0x80004005 (NS_ERROR_FAILURE)"  location: "JS frame :: chrome://calendar/content/calendar-dnd-listener.js :: invokeEventDragSession :: line 652"  data: no]

Comment 17

[Philipp Kewisch [:Fallen][📱📆]]

Since I cannot reproduce the Exception on Linux, it would be nice if someone else could give it a try.

Comment 18

[Markus Adrario [:Taraman]]

I debugged it on Windows, but couldn't find a solution.
But I had some findings which may help the more skilled:

When cancelling a drag - by either pressing ESC or letting the mouse button go in an area with no target - <handler event="dragend"> in [1] is called.

While executing this everything is equal in both cases. but in continuation after there is a difference:

When cancelling with ESC:
Execution continues directly with <handler event="mouseover"> in [2] and in that exact same moment the exception is thrown.

When dropping with no target:
Execution jumps back to [3] - the location the exception states - then back to <handler event="draggesture"> in [4].
Only after that it jumps to <handler event="mouseover"> in [2]

So the exception somehow comes from not returning to the right function call?
I believe it is not a problem in the Views, but in the backend code since it only appears on windows.

[1]: Line 443 of calendar-widgets.xml
http://mxr.mozilla.org/comm-central/source/calendar/base/content/widgets/calendar-widgets.xml#443

[2]: Line 352 of calendar-view-core.xml
http://mxr.mozilla.org/comm-central/source/calendar/base/content/calendar-view-core.xml#352

[3]: Line 652 of calendar-dnd-listener.js which is Line 655 in MXR for some reason
http://mxr.mozilla.org/comm-central/source/calendar/base/content/calendar-dnd-listener.js#655

[4]: Line 369 of calendar-view-core.xml
http://mxr.mozilla.org/comm-central/source/calendar/base/content/calendar-view-core.xml#369

Comment 19

[Philipp Kewisch [:Fallen][📱📆]]

Looking at http://hg.mozilla.org/releases/mozilla-1.9.1/annotate/d77750c8a7b8/widget/src/windows/nsDragService.cpp there are a few case where a NS_ERROR_FAILURE may occur:

* nsBaseDragService fails (line 196)
  - nsIDragService's suppress() was called previously without unsuppress()
* The number of items in the array is 0 (line 209)
* Creating the native data object fails (line 232,246)
* StartInvokingDragSession fails (line 263)
  - The native DND fails (line 316, 390)


Markus, could you check if the array of items passed to invokeDragService() is greater zero ?

Comment 20

[Markus Adrario [:Taraman]]

In calendar the array is always one (at least in the cases I tried.)
The invokeDragService() function is always called at the beginning of the drag-action. 
So it should not be a difference if I later on cancel the drag with ESC or not.

Comment 21

[Markus Adrario [:Taraman]]

What I forgot in the last comment:
Even if you mark more than one item and drag, only the item under the mouse on start of drg is dragged. Maybe this is a bug itself.

Further research showed, that the exception is thrown by StartInvokingDragSession() at [1]

[1]:
http://hg.mozilla.org/releases/mozilla-1.9.1/annotate/d77750c8a7b8/widget/src/windows/nsDragService.cpp#l390

Comment 22

[Philipp Kewisch [:Fallen][📱📆]]

Did you actually check this with a C debugger? In that case we should probably fix this bug by catching the exception and ignoring it, and file a core bug to find out why

http://hg.mozilla.org/releases/mozilla-1.9.1/annotate/d77750c8a7b8/widget/src/windows/nsDragService.cpp#l316

fails. They might tell us that the old dnd api is out of date though, so we might want to try moving to the new dom event driven dnd api.

Comment 23

[Markus Adrario [:Taraman]]

I checked it a little unusual by changing the type of exception in that line.
I got the altered exception - thus it must be coming from this line.

If you look at 
http://hg.mozilla.org/releases/mozilla-1.9.1/annotate/d77750c8a7b8/widget/src/windows/nsDragService.cpp#l348
you see that here the same compare statement leads to execution or cancellation of the drag&drop action which is used to return success or the exception at the end.

This seems to me, that the exception is normal behaviour of the nativeDragService and we must handle it.
By the way - if you try to drag a task in the task mode and press ESC, the same exception is thrown.

Comment 24

[Markus Adrario [:Taraman]]

Attachment: [checked in] error Handling to fix Exception

This patch adds error Handling code to the call of the nativeDragService's "invokeDragSession" function. (See above comments.)

Comment 25

[Philipp Kewisch [:Fallen][📱📆]]

Comment on attachment 375488 [details] [diff] [review]
[checked in] error Handling to fix Exception


>+    }
>+    catch (error) {

Only a small nit, our style guide uses:

} catch() {

I'll fix this before checkin.
r=philipp

Comment 26

[Philipp Kewisch [:Fallen][📱📆]]

Pushed to comm-central <http://hg.mozilla.org/comm-central/rev/790cf8238238>

-> FIXED

Comment 27

[Stefan Sitter [:ssitter]]

Verified fixed using Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1pre) Gecko/20090611 Calendar/1.0pre (BuildID: 20090611031611)