QMacStyle: smooth QMenu corners for real

It's been for years that QMenu's rounded corners in qmacstyle_mac were
done via QWidget::setMask(QRegion). Unfortunately, QRegion mask does not
work well with retina displays and also does not support translucency.
That's why in this change we explicitly make QMenu's background
transparent and then draw a rectangle with rounded corners in
QMacStyle::drawPrimitive(PE_PanelMenu). This not only gives much better
result than the mask-based approach, but also de-HIThemes QMenu.

As a consequence, QComboBoxPrivateContainer doesn't get any mask from
QMacStyle anymore. Therefore, when the mask is empty, we need to paint
PE_PanelMenu before invoking QFrame's paint event handler.

Made-with: Gabriel de Dietrich <gabriel.dedietrich@qt.io>
Change-Id: Ia9236176113f23b86e45507fa6ddf77236084ce3
Reviewed-by: Oleg Yadrov <oleg.yadrov@qt.io>
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@qt.io>

1 files changed, 0 insertions, 1 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoasystemsettings.mm b/src/plugins/platforms/cocoa/qcocoasystemsettings.mm
index 91fb6e973d..7c6f879b18 100644
--- a/src/plugins/platforms/cocoa/qcocoasystemsettings.mm
+++ b/src/plugins/platforms/cocoa/qcocoasystemsettings.mm
@@ -144,7 +144,6 @@ QHash<QPlatformTheme::Palette, QPalette*> qt_mac_createRolePalettes()
         }
         if (mac_widget_colors[i].paletteRole == QPlatformTheme::MenuPalette
                 || mac_widget_colors[i].paletteRole == QPlatformTheme::MenuBarPalette) {
-            pal.setBrush(QPalette::Background, qt_mac_toQColor([NSColor windowBackgroundColor]));
             pal.setBrush(QPalette::Highlight, qt_mac_toQColor([NSColor selectedMenuItemColor]));
             qc = qt_mac_toQColor([NSColor labelColor]);
             pal.setBrush(QPalette::ButtonText, qc);