Fix white text in tool tips and dock widget decorations

This was a regression in the custom styling. We no longer set
the panel property on the mainwindow but rely on qobject_cast
to style custom mainwindows.

Reviewed-by: thorbjorn

src/plugins/coreplugin/manhattanstyle.cpp

@@ -36,6 +36,8 @@
 #include <utils/qtcassert.h>
 #include <utils/stylehelper.h>
 
+#include <utils/fancymainwindow.h>
+
 #include <QtGui/QApplication>
 #include <QtGui/QComboBox>
 #include <QtGui/QDialog>
@@ -85,6 +87,9 @@ bool panelWidget(const QWidget *widget)
     if (qobject_cast<const QDialog *>(widget->window()))
         return false;
 
+    if (qobject_cast<const Utils::FancyMainWindow *>(widget))
+        return true;
+
     const QWidget *p = widget;
     while (p) {
         if (qobject_cast<const QToolBar *>(p) ||