I am trying to fix this from last two 2 or 3 days but failed. VS 2010 toolbox in asp application development(design mode or source) is not showing all controls(showing html
If you are working in WPF application and your Xaml is opened withxml, then make sure you right click and view designer, to get your toolbox controls enabled. (Toolbox controls seem to be active(enabled) only in designer mode). At least that was the case with me.