Description of Problem:
Wasting a lot of time without that feature.

Featre:
the basic idea is just to be able to duplicate a
layer as instance. All what you draw in the
original layer will be drawed in realtime in the
other layer and also the instance layer could be
modified as scale, rotation and flips..

examples of use:

Website:
A lot of times when you design a website you have
to set a style for all the boxes, if you change
something in one box you have to do the same
changes on the other boxes, in tha case could be
nice jus to duplicate the layer as instance and
move the instance layer to the correct positions
and design the website faster.

Illustration:
If you have to draw a face, could be nice to
duplicate the layer as instance and do a flip x of
the layer to have then a realtime system to draw a
face with the auto simetry.

Honestly i think that this feature could be really
usefull for a lot of cases and it´s something that
no other softwares have.