Within pvdevelop all widgets are supported.
In order to use custom widgets within Qt designer you have to copy the plugins to the qt designer plugins directory.
Linux:
Example for openSUSE 64 bit: cp /opt/pvb/designer/plugins/*.so /usr/lib64/qt4/plugins/designer/
Windows:
copy %PVBDIR%\win\bin\plugins\designer\pvb_designer_plugin.dll %QTDIR%\plugins\designer\ copy %PVBDIR%\win\bin\plugins\designer\qwt_designer_plugin.dll %QTDIR%\plugins\designer\
Custom widgets are the following:
QDraw QImage QGLWidget QVtkTclWidget QwtPlot QwtScale QwtThermo QwtKnob QwtCounter QwtWheel QwtSlider QwtCompass