[Qt][Mac] QWebView disappears when the system tries to hide the scrollbars.v5.0.0-rc1

https://bugs.webkit.org/show_bug.cgi?id=104116

This is a workaround for an issue in Qt that was
caused by Change-Id: I2000fa50d46b153e981ceafc12a53932a196382e
in qtbase.
Since we are drawing the scrollbars by ourselves, there is no
widget available that needs to be hidden by the style.
Therefore we have to disable transient scrollbar
animations on Mac.

Patch by: J-P Nurmi <jpnurmi@digia.com>

Reviewed by Simon Hausmann.

* WidgetSupport/QStyleFacadeImp.cpp:
(WebKit::QStyleFacadeImp::paintScrollBar):

Change-Id: Ia9ff6d6634aecfe574ba2842258fc003d4a5c665
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

1 files changed, 11 insertions, 16 deletions

diff --git a/Source/WebKit/qt/WidgetSupport/QStyleFacadeImp.cpp b/Source/WebKit/qt/WidgetSupport/QStyleFacadeImp.cpp
index bd6be1e47..7e2b8cab7 100644
--- a/Source/WebKit/qt/WidgetSupport/QStyleFacadeImp.cpp
+++ b/Source/WebKit/qt/WidgetSupport/QStyleFacadeImp.cpp
@@ -454,23 +454,18 @@ void QStyleFacadeImp::paintScrollBar(QPainter *painter, const QStyleFacadeOption
 
     MappedStyleOption<QStyleOptionSlider> opt(widget, proxyOption);
 
-#ifdef Q_OS_MAC
-    // FIXME: We also need to check the widget style but today ScrollbarTheme is not aware of the page so we
-    // can't get the widget.
-    if (m_style->inherits("QMacStyle"))
-        m_style->drawComplexControl(QStyle::CC_ScrollBar, &opt, painter, widget);
-    else
-#endif
-    {
-        // The QStyle expects the background to be already filled.
-        painter->fillRect(opt.rect, opt.palette.background());
-
-        const QPoint topLeft = opt.rect.topLeft();
-        painter->translate(topLeft);
-        opt.rect.moveTo(QPoint(0, 0));
-        style()->drawComplexControl(QStyle::CC_ScrollBar, &opt, painter, widget);
-        opt.rect.moveTo(topLeft);
+    if (m_style->inherits("QMacStyle")) {
+        // FIXME: Disable transient scrollbar animations on OSX to avoid hiding the whole webview with the scrollbar fade out animation.
+        opt.styleObject = 0;
     }
+
+    painter->fillRect(opt.rect, opt.palette.background());
+
+    const QPoint topLeft = opt.rect.topLeft();
+    painter->translate(topLeft);
+    opt.rect.moveTo(QPoint(0, 0));
+    style()->drawComplexControl(QStyle::CC_ScrollBar, &opt, painter, widget);
+    opt.rect.moveTo(topLeft);
 }
 
 QObject* QStyleFacadeImp::widgetForPainter(QPainter* painter)