Q 1) How do I create a transparent overlay with the VCLEdit
A) The standard VCL uses GDI which has no native support for transparency or antialiased drawing. You'll need to use an external library, such as:
GDI+ http://www.progdigy.com/?page_id=7 Graphics32 http://www.graphics32.org/ AggPas http://aggpas.org/
or a commercial library such as
DtpDocuments at http://www.simdesign.nl/contact.html
You can also do transparent overlays using the GDI directly with the AlphaBlend() GDI function.
Q 2) How do I draw antialiased lines or shapesEdit
A) See the answer for question 1