Fix crash in indeterminate progressbars on windows

Note that this is a surgical fix for 4.7 only.
In 4.8 we will add these checks at the top
of the styling functions or in the widgets instead.

Task-number:QTBUG-15227
Reviewed-by:gabi

1 files changed, 3 insertions, 1 deletions

diff --git a/src/gui/styles/qwindowsstyle.cpp b/src/gui/styles/qwindowsstyle.cpp
index 654be3c230..32a6d8d110 100644
--- a/src/gui/styles/qwindowsstyle.cpp
+++ b/src/gui/styles/qwindowsstyle.cpp
@@ -2397,8 +2397,10 @@ void QWindowsStyle::drawControl(ControlElement ce, const QStyleOption *opt, QPai
 #ifndef QT_NO_PROGRESSBAR
     case CE_ProgressBarContents:
         if (const QStyleOptionProgressBar *pb = qstyleoption_cast<const QStyleOptionProgressBar *>(opt)) {
-
             QRect rect = pb->rect;
+            if (!rect.isValid())
+                return;
+
             bool vertical = false;
             bool inverted = false;