Bug 26045 – The Qt Style Sheets are not applied on webkit scrollbars

• Component: Layout and Rendering
• Status: RESOLVED INVALID

[Vincent Ordy]

The Qt Style Sheets set with setStyleSheet() on the QWebView are not applied on webkit scroll bars.

It seems to happen because of the QStyleSheetStyleSelector::attribute() and QStyleSheetStyleSelector::nodeNames() functions used by StyleSelector::styleRulesForNode(). They both use the widget metadata to get the widget type name and properties in order to find out which rules to apply.

A quick fix is to have ScrollbarThemeQt inherit from QScrollbar and use "this" as widget for drawComplexControl().
-    p.drawComplexControl(QStyle::CC_ScrollBar, *opt);
+    p.style->drawComplexControl(QStyle::CC_ScrollBar, opt, p.painter, this);

[Kent Hansen]

Please provide a testcase (in the form of a compileable Qt app, for example).

[Vincent Ordy]

Created attachment 50446 [details]
Testcase

[Vincent Ordy]

This testcase creates 2 windows.  Both have a QScrollArea which contains a QWebView. I do setStyleSheet("QScrollBar { background: blue; }") on both windows.

The style of the first is QWindowsStyle, and the second's is QMotifStyle. The QWebView scrollbar does use the style set by setStyle.

However, it does not use the one set by setStyleSheet("QScrollBar {...}"). Like I said before, it happens because the Qt Style Sheets system uses metadata to find out the type of an object. Since a ScrollbarThemeQt is not a QScrollbar, the style sheet for QScrollbar is not used.

[Kent Hansen]

(In reply to comment #3)
> This testcase creates 2 windows.  Both have a QScrollArea which contains a
> QWebView. I do setStyleSheet("QScrollBar { background: blue; }") on both
> windows.
> 
> The style of the first is QWindowsStyle, and the second's is QMotifStyle. The
> QWebView scrollbar does use the style set by setStyle.
> 
> However, it does not use the one set by setStyleSheet("QScrollBar {...}"). Like
> I said before, it happens because the Qt Style Sheets system uses metadata to
> find out the type of an object. Since a ScrollbarThemeQt is not a QScrollbar,
> the style sheet for QScrollbar is not used.

Thanks for the testcase.
Hmm, with r33755 and Qt 4.6 trunk the QWebView scrollbars don't even respect setStyle()! It did in an older version, like you said, so this is a regression.

[Kent Hansen]

(In reply to comment #4)
> Hmm, with r33755 and Qt 4.6 trunk

Sorry, that should be r55658.

[Jocelyn Turcotte]

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