Add mockup toolset?

[Herbert Grunwald <hgrunw gmail com>]

Hi, Dia is excellent, but a feature that could be easily added and
would boost Dia usage a lot is to add a mockup toolset. Lately,
Balsamiq Mockups have gained attention, but their product is less
flexible than Dia, so there's an excellent opportunity for gaining
some general acceptance. AFAICS it's also rather easy to add the
required bits to Dia.