Fix crash on populating style data to tabbar without parent
This resolves Bug 1966

diff --git a/src/styles/qcommonstyle.cpp b/src/styles/qcommonstyle.cpp
index f6319a4..0bad0a5 100644
--- a/src/styles/qcommonstyle.cpp
+++ b/src/styles/qcommonstyle.cpp
@@ -468,41 +468,43 @@
 							ceData.tabBarData.identIndexMap[currentTab->identifier()] = tb->indexOf(currentTab->identifier());
 						}
 					}
-					updateObjectTypeListIfNeeded(tb->parent());
-					if ((const_cast<QObject*>(tb->parent())->controlElementDataPrivateObject())->isQTabWidget) {
-						const QTabWidget *tw = static_cast<const QTabWidget*>(tb->parent());
-						QWidget *cw;
-						cw = tw->cornerWidget(Qt::TopLeft);
-						if (cw) {
-							updateObjectTypeListIfNeeded(cw);
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopLeft].widgetObjectTypes = (const_cast<QWidget*>(cw)->controlElementDataObject())->widgetObjectTypes;
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopLeft].geometry = cw->geometry();
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopLeft].rect = cw->rect();
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopLeft].pos = cw->pos();
-						}
-						cw = tw->cornerWidget(Qt::TopRight);
-						if (cw) {
-							updateObjectTypeListIfNeeded(cw);
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopRight].widgetObjectTypes = (const_cast<QWidget*>(cw)->controlElementDataObject())->widgetObjectTypes;
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopRight].geometry = cw->geometry();
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopRight].rect = cw->rect();
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopRight].pos = cw->pos();
-						}
-						cw = tw->cornerWidget(Qt::BottomLeft);
-						if (cw) {
-							updateObjectTypeListIfNeeded(cw);
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomLeft].widgetObjectTypes = (const_cast<QWidget*>(cw)->controlElementDataObject())->widgetObjectTypes;
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomLeft].geometry = cw->geometry();
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomLeft].rect = cw->rect();
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomLeft].pos = cw->pos();
-						}
-						cw = tw->cornerWidget(Qt::BottomRight);
-						if (cw) {
-							updateObjectTypeListIfNeeded(cw);
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomRight].widgetObjectTypes = (const_cast<QWidget*>(cw)->controlElementDataObject())->widgetObjectTypes;
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomRight].geometry = cw->geometry();
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomRight].rect = cw->rect();
-							ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomRight].pos = cw->pos();
+					if ( tb->parent() ) {
+						updateObjectTypeListIfNeeded(tb->parent());
+						if ((const_cast<QObject*>(tb->parent())->controlElementDataPrivateObject())->isQTabWidget) {
+							const QTabWidget *tw = static_cast<const QTabWidget*>(tb->parent());
+							QWidget *cw;
+							cw = tw->cornerWidget(Qt::TopLeft);
+							if (cw) {
+								updateObjectTypeListIfNeeded(cw);
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopLeft].widgetObjectTypes = (const_cast<QWidget*>(cw)->controlElementDataObject())->widgetObjectTypes;
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopLeft].geometry = cw->geometry();
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopLeft].rect = cw->rect();
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopLeft].pos = cw->pos();
+							}
+							cw = tw->cornerWidget(Qt::TopRight);
+							if (cw) {
+								updateObjectTypeListIfNeeded(cw);
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopRight].widgetObjectTypes = (const_cast<QWidget*>(cw)->controlElementDataObject())->widgetObjectTypes;
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopRight].geometry = cw->geometry();
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopRight].rect = cw->rect();
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_TopRight].pos = cw->pos();
+							}
+							cw = tw->cornerWidget(Qt::BottomLeft);
+							if (cw) {
+								updateObjectTypeListIfNeeded(cw);
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomLeft].widgetObjectTypes = (const_cast<QWidget*>(cw)->controlElementDataObject())->widgetObjectTypes;
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomLeft].geometry = cw->geometry();
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomLeft].rect = cw->rect();
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomLeft].pos = cw->pos();
+							}
+							cw = tw->cornerWidget(Qt::BottomRight);
+							if (cw) {
+								updateObjectTypeListIfNeeded(cw);
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomRight].widgetObjectTypes = (const_cast<QWidget*>(cw)->controlElementDataObject())->widgetObjectTypes;
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomRight].geometry = cw->geometry();
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomRight].rect = cw->rect();
+								ceData.tabBarData.cornerWidgets[QStyleControlElementTabBarData::CWL_BottomRight].pos = cw->pos();
+							}
 						}
 					}
 				}