QWidgets/CommonStyle: Fix tooltip drawing under HighDPI

Delegating the border painting to qDrawPlainRect ensures that there are
no off-by-one pixel issues.

Task-number: QTBUG-61849
Change-Id: I56dc849da80fad00d02a0f9c60dbb621e6de7c48
Reviewed-by: Michael Winkelmann <michael.winkelmann@qt.io>
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

1 files changed, 2 insertions, 7 deletions

diff --git a/src/widgets/styles/qcommonstyle.cpp b/src/widgets/styles/qcommonstyle.cpp
index 64a3a73b0d..a8f8c97776 100644
--- a/src/widgets/styles/qcommonstyle.cpp
+++ b/src/widgets/styles/qcommonstyle.cpp
@@ -572,13 +572,8 @@ void QCommonStyle::drawPrimitive(PrimitiveElement pe, const QStyleOption *opt, Q
         break; }
 #endif // QT_NO_SPINBOX
     case PE_PanelTipLabel: {
-        QBrush oldBrush = p->brush();
-        QPen oldPen = p->pen();
-        p->setPen(QPen(opt->palette.toolTipText(), 0));
-        p->setBrush(opt->palette.toolTipBase());
-        p->drawRect(opt->rect.adjusted(0, 0, -1, -1));
-        p->setPen(oldPen);
-        p->setBrush(oldBrush);
+        const QBrush brush(opt->palette.toolTipBase());
+        qDrawPlainRect(p, opt->rect, opt->palette.toolTipText().color(), 1, &brush);
         break;
     }
 #if QT_CONFIG(tabbar)