Bug 358047

Summary: Extremely sluggish and unusable drag&drop
Product: [Plasma] plasmashell Reporter: Nikos Chantziaras <realnc>
Component: generalAssignee: David Edmundson <kde>
Status: RESOLVED FIXED    
Severity: normal CC: bshah, eliashogstvedt, jameshy64, plasma-bugs-null
Priority: NOR    
Version First Reported In: 5.5.3   
Target Milestone: 1.0   
Platform: Gentoo Packages   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: Video demonstrating the bug

Description Nikos Chantziaras 2016-01-16 02:12:16 UTC 
(I am not sure if Plasma is the correct choice to report this bug against.)

Drag&drop is not usable due to its slowness. When dragging something with the mouse, the object being dragged stays behind the current mouse position by several seconds.

I've made a video that demonstrates this bug:

https://www.youtube.com/watch?v=2_etvLIzlKQ

(I will also attach the video to this bug report.)

Note that in the video, I used Dolphin for the demonstration, but the bug is there with everything else too (like for desktop icons or dragging a process line in ksysguard.)

Suspending desktop compositing does not have any effect. Drag operations are extremely slow even without compositing.

My system:

Gentoo Linux AMD64
KDE Plasma 5.5.3
KDE Frameworks 5.18.0
KDE Applications 15.08.3
Qt 5.5.1
X.Org server 1.17.4
NVidia driver 352.63
Kernel 4.1.15

Reproducible: Always
Comment 1 Nikos Chantziaras 2016-01-16 02:14:17 UTC 
Created attachment 96669 [details]
Video demonstrating the bug
Comment 2 CapsAdmin 2016-03-04 11:54:35 UTC 
I have this problem as well when I have an application rendering something every frame in the background.
Comment 3 Nikos Chantziaras 2016-03-04 16:04:08 UTC 
(In reply to CapsAdmin from comment #2)
> I have this problem as well when I have an application rendering something
> every frame in the background.

For this happens without even a single application running. Just logging in to KDE without starting anything, the problem is there.
Comment 4 CapsAdmin 2016-03-04 16:30:06 UTC 
(In reply to Nikos Chantziaras from comment #3)
> (In reply to CapsAdmin from comment #2)
> > I have this problem as well when I have an application rendering something
> > every frame in the background.
> 
> For this happens without even a single application running. Just logging in
> to KDE without starting anything, the problem is there.

I understand and I think it's somewhat constantly slow here too but for it to get as slow as in your video I'd have to be watching a video or something that refreshes a lot in the background.
Comment 5 Nikos Chantziaras 2016-08-02 10:37:54 UTC 
Forgot to close this. It was a Qt issue. Recent versions of Qt have fixed it.