I have recently upgraded our ribbon-based WPF application from build v10.2.0532 to build 13.2.590.0 and am observing the same behavior: I cannot move the application window anymore. I futher notice a couple of data binding issues in that area:
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'ElementName=PART_Popup'. BindingExpression:Path=HasDropShadow; DataItem=null; target element is 'PopupButton' (Name=''); target property is 'NoTarget' (type 'Object')
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'ElementName=PART_Popup'. BindingExpression:Path=HasDropShadow; DataItem=null; target element is 'QuickAccessToolBarOverflowButton' (Name='OverflowButton'); target property is 'NoTarget' (type 'Object')
I have been doing a side-by-side comparison with the code in ProductSamples\RibbonSamples\Demo\DocumentEditor but so far have not spotted any non-trivial difference (e.g., different name string or icon paths). I have inserted the "NonClientArea" attribute as suggested above but still no improvement.