ads200002@gmail.com Reporter
	Description • 8 years ago

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:49.0) Gecko/20100101 Firefox/49.0
Build ID: 20160522030240

Steps to reproduce:

Open a Firefox window with at least two tabs. Drag a tab into a new window (i.e. drag the tab out of the tab bar).


Actual results:

The thumbnail of the tab is left stuck on the screen.
See attached screenshot. In this screenshot, the thumbnail for a Google Calendar tab is stuck on a window with BMO open.


Expected results:

The thumbnail of the tab should've disappeared upon release.

	:Gijs (he/him)
	Comment 1 • 8 years ago

Does this happen every time you move a tab? Does it happen if you test on a clean profile? ( https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles )

	ads200002@gmail.com Reporter
	Comment 2 • 8 years ago

It doesn't happen every time I move a tab, but it happens every time a tab is dragged out of the tab bar to create a new window (moving a tab into an existing window doesn't recreate the bug).
I tried a clean profile and it still happens, will attach another screenshot.

	ads200002@gmail.com Reporter
	Comment 3 • 8 years ago

You can see the thumbnail/preview of the OMG! Ubuntu! tab stuck on the 'Get Firefox for Android' link.

	:Gijs (he/him)
	Comment 4 • 8 years ago

I'm very sorry, but I can't reproduce this, so I have to ask you some more questions...

- When dragging a tab, normally that tab becomes the selected tab, and so I don't really understand how you manage to drag the tab and then have it drop on top of an existing tab. Are you using any keyboard modifiers when dragging? Any external tools that could be interfering with this?

- What version of Ubuntu and GTK are you using?
- If you're a regular nightly user, do you know if this regressed (ie did it work a week or two ago), and if so, any chance you could look for a regression window with mozregression? ( http://mozilla.github.io/mozregression/ )

	ads200002@gmail.com Reporter
	Comment 5 • 8 years ago

- I'm dragging the tab outside of the tab bar, so I'm not dropping it on an existing tab, I'm making a new window by dragging the tab. No keyboard modifiers, I don't think any external tools will be interfering.
- I'm using Ubuntu Yakkety (16.10) and GTK 3.18.9 (libgtk-3-0 3.18.9-1ubuntu3, which is the same version as in Ubuntu 16.04).
- I'm not sure when it regressed, might have been a week or so before reporting but I'm really not sure, might have been there when I started using Nightly because I only started using it about a week or so before reporting this bug. I could search through Nightly versions but that's going to take time, I know it's a long wait but I might have time to do it in about a month or so (if the regression still exists then).
- Note: Bug still occurs in Nightly 49.0a1 (2016-06-01)

	:Gijs (he/him)
	Comment 6 • 8 years ago

(In reply to ads200002 from comment #5)
> - I'm dragging the tab outside of the tab bar, so I'm not dropping it on an
> existing tab, I'm making a new window by dragging the tab. No keyboard
> modifiers, I don't think any external tools will be interfering.

I understand you're not dragging it within the tab bar. What I don't understand is how the image of the dragged tab ends up on another tab, if the tab you're dragging is selected as you're dragging it.

> - I'm using Ubuntu Yakkety (16.10) and GTK 3.18.9 (libgtk-3-0
> 3.18.9-1ubuntu3, which is the same version as in Ubuntu 16.04).

OK. Does this reproduce in safe mode? Can you paste the graphics section from about:support ?

This feels like a graphics / gtk issue more than anything, so going to move this to the relevant component.

	ads200002@gmail.com Reporter
	Comment 7 • 8 years ago

(In reply to :Gijs Kruitbosch from comment #6)

> I understand you're not dragging it within the tab bar. What I don't
> understand is how the image of the dragged tab ends up on another tab, if
> the tab you're dragging is selected as you're dragging it.

I don't know, the image of the tab ends up 'stuck' on the screen. Even if you minimize Nightly or switch to another window or desktop the image remains 'stuck' on the screen. The only way to get rid of it is to either close Nightly or move a tab slightly in the original window to create a tab image there (it then disappears, if you don't drag it out and create a new 'stuck' image).

> OK. Does this reproduce in safe mode? Can you paste the graphics section
> from about:support ?

I can reproduce it in Safe Mode.
The paste from about:support is below (I'm using the open-source Nouveau driver because I can't login with the Nvidia one)

Graphics
--------

Features
Compositing: Basic
Asynchronous Pan/Zoom: wheel input enabled
Hardware H264 Decoding: No
GPU #1
Active: Yes
Description: nouveau -- Gallium 0.4 on NV63
Vendor ID: nouveau
Device ID: Gallium 0.4 on NV63
Driver Version: 2.1 Mesa 11.2.1

Diagnostics
AzureCanvasAccelerated: 0
AzureCanvasBackend: skia
AzureContentBackend: cairo
AzureFallbackCanvasBackend: none
CairoUseXRender: 0
webglRendererMessage:
Decision Log
HW_COMPOSITING:
blocked by default: Acceleration blocked by platform
blocked by runtime: Acceleration blocked by safe-mode

	:Gijs (he/him)
	Comment 8 • 8 years ago

Karl/Milan, thoughts on whether this is a GTK or Graphics issue and/or other diagnostics steps?

	Milan Sreckovic [:milan] (needinfo for best results)
	Comment 9 • 8 years ago

Probably not "graphics" in the sense that it would end up in Core:Graphics, but likely something in the drag/drop.

	Karl Tomlinson (:karlt)
	Comment 10 • 8 years ago

Yes.  Sounds like the DnD state getting stuck, until it is reset with the next drag.
The fact that a new drag can be initiated suggests that Gecko thinks the previous drag has finished.

	Karl Tomlinson (:karlt)
	Comment 11 • 8 years ago

Does unchecking "Enable multi-process Nightly" in the Preferences workaround the bug?

(I see from bug 1172491 that safe-mode is not really safe now.)

	ads200002@gmail.com Reporter
	Comment 12 • 8 years ago

(In reply to Karl Tomlinson (back June 7 ni?:karlt) from comment #11)
> Does unchecking "Enable multi-process Nightly" in the Preferences workaround
> the bug?

Yes it does. It also makes the tab preview translucent, whereas with multi-process enabled the tab preview is completely opaque.

	Karl Tomlinson (:karlt)
	Comment 13 • 8 years ago

Thanks.  Not reproducing here with GTK+-3.18.7 and kwin.  Perhaps the interaction with the window compositor is different.

	Jim Mathies [:jimm]
	Comment 14 • 8 years ago

Neil, any ideas here?

	ads200002@gmail.com Reporter
	Comment 15 • 8 years ago

I'm using GNOME Flashback installed on standard Ubuntu (ubuntu-bug calls it GNOME-Flashback:Unity). I use it with Metacity, which might explain why it's not reproducible with kwin.

	Karl Tomlinson (:karlt)
	Comment 16 • 8 years ago

Do you know whether metacity is compositing or not?
(I'm surprised to see Ubuntu 16.10 providing a metacity package.)

	Neil Deakin
	Comment 17 • 8 years ago

I can't reproduce this either, but some questions for the reporter:

1. Does this issue always occur no matter where you drag the tab to? For example, dragging upwards, dropping only on the Firefox window, dropping only on another window, dragging slower or faster, etc?

2. Does the feedback thumbnail image remain if you abort the drag (press escape)?

3. Just to clarify, the leftover feedback thumbnail remains in the same place if you, after dropping, move the main window? Or does the thumbnail then move with the window or disappear?

Are you able to test the following build to see if the issue occurs:

http://archive.mozilla.org/pub/firefox/try-builds/neil@mozilla.com-13b706a22d40d2034d5110310dabddeabd57437e/try-linux-debug/firefox-49.0a1.en-US.linux-i686.tar.bz2

	ads200002@gmail.com Reporter
	Comment 18 • 8 years ago

(In reply to Karl Tomlinson (ni?:karlt) from comment #16)
> Do you know whether metacity is compositing or not?
> (I'm surprised to see Ubuntu 16.10 providing a metacity package.)

Yes it's compositing (according to dconf).

(In reply to Neil Deakin from comment #17)
> 1. Does this issue always occur no matter where you drag the tab to? For
> example, dragging upwards, dropping only on the Firefox window, dropping
> only on another window, dragging slower or faster, etc?

Yes, it seems to happen no matter how I do it.

> 2. Does the feedback thumbnail image remain if you abort the drag (press
> escape)?

If I press escape while dragging, the feedback thumbnail does indeed remain.

> 3. Just to clarify, the leftover feedback thumbnail remains in the same
> place if you, after dropping, move the main window? Or does the thumbnail
> then move with the window or disappear?

The leftover feedback thumbnail remains in the same place after dropping no matter what I do with windows unless if I close Nightly or if I drag a tab in the original window (which the tab with the broken thumbnail was dragged from). Also, if I drag a tab in the original window to close the leftover thumbnail, the thumbnail which comes up as I drag the new tab is the thumbnail for the first tab which I dragged out (the 'stuck' thumbnail effectively moves to the new tab (I don't mean New Tab)), then when I release it disappears.

Further, if I drag one tab into a new window (reproducing the bug) and then drag a second tab from the original window into a second new window then I get a box the size of the tab preview stuck on the screen which has the image of the bit of the page where I left the preview. I took a screenshot of it (which I will attach as 'Dragging a second tab.png'), I then took a screenshot after I took the first screenshot, where the box goes black (probably because the screen goes black when I take the screenshot, I'll attach this as 'Dragging a second tab after screenshot.png'). I'll see if I can make some GIFs of what's happening (this must be very confusing in words).
 
> Are you able to test the following build to see if the issue occurs:
> 
> http://archive.mozilla.org/pub/firefox/try-builds/neil@mozilla.com-
> 13b706a22d40d2034d5110310dabddeabd57437e/try-linux-debug/firefox-49.0a1.en-
> US.linux-i686.tar.bz2

I'll test that in a sec.

	ads200002@gmail.com Reporter
	Comment 19 • 8 years ago

Here's a GIF to show the bug. Ignore any other graphical abnormalities, that's just the screen recording software not working perfectly/the limitations of GIF. The GIF shows the tab preview sticking to the screen.

I won't attach PNGs because I think this GIF does the job.

Neil Deakin, that build simply doesn't load. I can't seem to run it with `./` in Terminal either (I did `chmod +x` it) so I don't know what's not working with it.

	ads200002@gmail.com Reporter
	Comment 20 • 8 years ago

This seems to be fixed as of 50.0a1 (2016-06-17)

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	Comment 21 • 8 years ago

I was too hasty. I'm changing this back to UNCONFIRMED because the bug still exists in 49.0a2 (2016-06-18) (Developer Edition). Hopefully it can be fixed there before 49 Branch is released as stable.

	ads200002@gmail.com Reporter
	Comment 22 • 8 years ago

(Note: This bug doesn't exist in stable (47) or Beta (48))

	:Gijs (he/him)
	Comment 23 • 8 years ago

(In reply to ads200002 from comment #21)
> Hopefully it can be fixed
> there before 49 Branch is released as stable.

In order to do that we'd need to know what fixed it and uplift it. Unfortunately nobody else has managed to reproduce this yet. Can you check? Mozregression (comment #4) has a "--find-fix" flag that should help with determining what build fixed this.

	ads200002@gmail.com Reporter
	Comment 24 • 7 years ago

Now it seems there's no preview at all, is this correct? Was this feature removed (see the GIF to be reminded of what I was talking about)?

	:Gijs (he/him)
	Comment 25 • 7 years ago

(In reply to ads200002 from comment #24)
> Now it seems there's no preview at all, is this correct? Was this feature
> removed (see the GIF to be reminded of what I was talking about)?

I still see previews on Nightly (tested on OS X) and am not aware of any plans to remove them. I suggest you file a new bug with more details (an exact regression window, what window manager / OS you're seeing this on, etc.) if they've disappeared for you.

	ads200002@gmail.com Reporter
	Comment 26 • 6 years ago

Apologies for not getting round to doing this.