Infragistics has their own version of a GradientFormHeader so this one really wouldn't make a whole lot of sense. As for the other two, no we are not. Here is the reasoning behind this. We initially did this for the DevExpress controls. The GradientFormHeader on the DevEx is OK, but the MaintenanceFormToolbar and the BrowseDialog for the DevExpress have already starting growing apart from the standard controls.
In the next update, the MaintenanceFormToolstrip, BrowseDialog, and all other run-time components will have full localization support (pre-translated) for English, Portuguese, Spanish, German, and French. Since the toolbars and the BrowseDialog require a totally separate code base this becomes very cumbersome to maintain. Additionally, the BrowseDialog is a huge undertaking in itself to dynamcially create the form with all of the different control collections. It just isn't worth the staff and energy required to keep all of this up to date.
I recommend using our Themes if you are looking for theme support and use the Infragistics editor controls, such as the TextBox, etc. This will allow you to take full advantage of the BrowseDialog and our Messaging interface without having the look of two different themes.