More generally, this may just mean that the click-and-hold threshold for fine-grained scrolling is too aggressive.

Thanks for a bug report. I'm not sure I follow, but it's also a quite long time since you reported, thus it can be likely fixed in current stable versions. Could you retest and, if still reproducible for you, report exact versions of gtk3 and evolution you use, please?

I can just grab the "scrollbar button, the one which shows what the scroll position is with respect of the whole content of the message list" without any problem, but it's possible you are talking about a different way of scrolling. I use current development version of evolution (to be 3.12.92 soon) and gtk3-3.14.6-1.fc21.x86_64.

(In reply to Milan Crha from comment #2)
> evolution (to be 3.12.92 soon)

Oops, it's supposed to be 3.15.92.

(In reply to Milan Crha from comment #2)
> Thanks for a bug report. I'm not sure I follow, but it's also a quite long
> time since you reported, thus it can be likely fixed in current stable
> versions. Could you retest and, if still reproducible for you, report exact
> versions of gtk3 and evolution you use, please?
> 
> I can just grab the "scrollbar button, the one which shows what the scroll
> position is with respect of the whole content of the message list" without
> any problem, but it's possible you are talking about a different way of
> scrolling. I use current development version of evolution (to be 3.12.92
> soon) and gtk3-3.14.6-1.fc21.x86_64.

I still see this issue with current evolution and gtk3 in Debian unstable.  Evolution is a snapshot from the 3.12.9+ stable git branch, and gtk3 is 3.14.5.

(In reply to Josh Triplett from comment #4)
> I still see this issue with current evolution and gtk3 in Debian unstable. 
> Evolution is a snapshot from the 3.12.9+ stable git branch, and gtk3 is
> 3.14.5.

Okay. Could you help me to understand what I should do to reproduce the issue and what to look for, please?

(In reply to Milan Crha from comment #5)
> (In reply to Josh Triplett from comment #4)
> > I still see this issue with current evolution and gtk3 in Debian unstable. 
> > Evolution is a snapshot from the 3.12.9+ stable git branch, and gtk3 is
> > 3.14.5.
> 
> Okay. Could you help me to understand what I should do to reproduce the
> issue and what to look for, please?

Have a folder with at least a few hundred mails in it, so there's lots of scrolling to do.  Click and hold on the scroll thumb, drag it a very tiny distance, and wait a moment.  The scroll thumb will turn thin, indicating "fine scrolling" mode, despite having moved the scroll thumb.  Then, because of the transition to "fine scrolling" mode, I can't actually scroll the whole list at a reasonable speed.

*Without* fine scrolling mode, I can easily scroll a message list a few lines at a time by moving the scrollbar a few pixels at a time; because of that minimal mouse movement, I frequently trigger fine scrolling mode when not wanted.

Thanks for the update. I see it too now (I never moved only a few pixels and waited, thus it behaved fine for me, because of no fine scrolling). I tried to reproduce this in a gtk3-demo, because Evolution doesn't use its own
scrollbars - that all is gtk, and I can reproduce it there too, thus I move this there.

Thanks for taking the time to report this.

This particular bug has already been reported into our bug tracking system, but we are happy to tell you that the problem has already been fixed in the code repository for 3.16. The fine scrolling trigger delay has been increased, and we're working on new ideas with the design team.

*** This bug has been marked as a duplicate of bug 728739 ***