Arbitrary scaling?

[Greg Trounson <gregt maths otago ac nz>]

Greetings,

I am wondering if there is a way in Dia to scale multiple selections? 
At the moment, if I marquee-select a group of objects, dragging a corner
of an object only resizes that one object.

If I first "group" the objects, then try to drag the black corners
defining the group, nothing happens.

On this topic, does anyone know if there is plans to implement a
user-defined scale, so that the rulers on the top and left sides can
display, say, a scale of 1:50?  This would be very handy for any
plan-related work.

thank you,
Greg