Only unset the QWidget stylesheet if it was previously set to a custom one

Less potential side-effects.

src/widgets/ViewContainer.cpp

@@ -201,8 +201,12 @@ void TabbedViewContainer::konsoleConfigChanged()
 
     if (KonsoleSettings::tabBarUseUserStyleSheet()) {
         setCssFromFile(KonsoleSettings::tabBarUserStyleSheetFile());
+        _stylesheetSet = true;
     } else {
-        setStyleSheet(QString());
+        if (_stylesheetSet) {
+            setStyleSheet(QString());
+            _stylesheetSet = false;
+        }
     }
 }
 

src/widgets/ViewContainer.h

@@ -235,6 +235,8 @@ private:
         }
     };
 
+    bool _stylesheetSet = false;
+
     QHash<const QWidget *, TabIconState> _tabIconState;
     ViewManager *_connectedViewManager;
     QMenu *_contextPopupMenu;