1290196 - Firefox does not use standard GTK Scrollbar

Status: RESOLVED INVALID

(Core :: Widget: Gtk, defect)

Description

[zwielichtauge]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:47.0) Gecko/20100101 Firefox/47.0
Build ID: 20160606113944

Steps to reproduce:

I am creating a GTK3 theme. I set the following rules:

.scrollbar {
    /* ... */
    background-color: alpha(@scrollbar_track_color, 0.5);
    background-image: none;
    background-size: 0;
    /* ... */
}

.scrollbar.overlay-indicator {
    background-color: transparent;
}


Actual results:

All GTK3 Programs use the rules and show a scrollbar with a transparent overlay bar which when hovered gets colored in the specified color (  alpha(@scrollbar_track_color, 0.5) ).
Firefox does not. Firefox shows an overlay bar which is not transparent and using some of my theme colors - but since I use a transparent scrollbar slider, it is not visible at all with this overlay bar. Why does FF not just use standard GTK theme colors?


Expected results:

The scrollbar overlay bar should be styled according to the rules specified in the gtk3-theme.

Comment 1

[Karl Tomlinson (:karlt)]

(In reply to zwielichtauge from comment #0)
> Firefox shows an overlay bar which is not transparent and
> using some of my theme colors -

Firefox does not use overlay scrollbars, which means that .overlay-indicator will not match, but could you attach some screenshots please, because I don't know what you are describing as "overlay bar".

> but since I use a transparent scrollbar
> slider, it is not visible at all with this overlay bar.

What usually makes the transparent slider visible?

> Why does FF not just use standard GTK theme colors?

It aims to, but this bug tracks finding why not in this case.

As you've probably discovered, GTK themes for one GTK3 version don't work in another, so can you indicate the GTK version for which you are writing the theme please?

Comment 2

[zwielichtauge]

Attachment: scrollbar.png

A Screenshot showing the problem, the usually more transparent slider has been made more visible

Comment 3

[zwielichtauge]

I use GTK Version 3.18.9-1ubuntu3.1

The slider is usually mostly transparent, but not completely, but if you look at the screenshot you might understand the problem since I have changed transparency from alpha(0.3) to alpha(0.8) in it.

I can give you the full slider css:

.scrollbar.slider {
    background-color: alpha(mix(@button_bg_color, @base_color, 0.6), 0.8);/* alpha: 0.3  */
    border-radius: 7px;
}

On Hover, i remove the transparency so it can be used properly. The idea is to have a non-disturbing, yet visible slider which works just well in any other gtk3 application. Here the problem comes from the "overlay bar" which is what is drawn below the slider- usually it should be transparent with my rule

.scrollbar.overlay-indicator {
    background-color: transparent;
}

but in firefox it is not, and changing the rules for .scrollbar or .scrollbar.overlay-indicator does not have any effect on it, it indicates to me that firefox does not use these rules at all, while it does use the rule for the slider which is drawn accordingly to my css.

Comment 4

[zwielichtauge]

(In reply to Karl Tomlinson (:karlt) from comment #1)
> (In reply to zwielichtauge from comment #0)
> > Firefox shows an overlay bar which is not transparent and
> > using some of my theme colors -
> 
> Firefox does not use overlay scrollbars, which means that .overlay-indicator
> will not match, but could you attach some screenshots please, because I
> don't know what you are describing as "overlay bar".
> 
> > but since I use a transparent scrollbar
> > slider, it is not visible at all with this overlay bar.
> 
> What usually makes the transparent slider visible?
> 
> > Why does FF not just use standard GTK theme colors?
> 
> It aims to, but this bug tracks finding why not in this case.
> 
> As you've probably discovered, GTK themes for one GTK3 version don't work in
> another, so can you indicate the GTK version for which you are writing the
> theme please?

My above comments are a reply to your comment. Sorry im new to BugZilla :)

Comment 5

[Karl Tomlinson (:karlt)]

(In reply to zwielichtauge from comment #3)
> Here the problem comes from the "overlay bar" which
> is what is drawn below the slider- usually it should be transparent with my
> rule
> 
> .scrollbar.overlay-indicator {
>     background-color: transparent;
> }
> 
> but in firefox it is not, and changing the rules for .scrollbar or
> .scrollbar.overlay-indicator does not have any effect on it, it indicates to
> me that firefox does not use these rules at all, while it does use the rule
> for the slider which is drawn accordingly to my css.

Yes, Firefox won't use the overlay-indicator rule because it does not use an
overlay indicator.  Scrollbars in Firefox are always shown.  The track for (behind) the slider can be styled with .scrollbar.trough.

Comment 6

[zwielichtauge]

Ok thank you very much for this information and sorry I have filed a bug for it.