Hi, I'm working on dock-based application and recently I've decided to use my own titleBarWidgets. It works great, but the downfall is we lose native fell & look when going into undocked state (at least on Win7).

So what I was trying to do was to connect to topLevelChanged signal and then in slot either set my custom widget as titleBarWidget (going into docked state) or set titleBarWidget to 0 (undocked), thus returning native window decorations. So code looks roughly like this:

Qt Code: 
  1. QWidget* titleBar;
  2. ...
  3. QObject::connect( this, SIGNAL(topLevelChanged(bool)), this, SLOT(setUseNativeTitleBar(bool)) );
  4. ...
  5. void setUseNativeTitleBar(bool native)
  6. {
  7.     if ( native ) {
  8.         // restoring native
  9.         setTitleBarWidget(0);
  10.     } else {
  11.         // using custom
  12.         setTitleBarWidget(titleBar);
  13.     }
  14. }
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Now it seems to work just fine, but more than often it results in assertion failure during undocking (especially when stacking widgets horizontally):

ASSERT: "!(item.flags & QDockAreaLayoutItem::GapItem)" in file widgets\qdockarealayout.cpp, line 1082

So my question is: is changing titleBarWidget in this manner even possible? If so, how to get it working?

Oh yes, and I'm using Qt 4.7.1.