garageCube

Instead of defining each pixel as a rectangle along a line, being able to define each LED as independent nodes along a line.
This would allow a tighter work in installations with led bulbs in line, for example being able to define a fixed distance between the different pixels.

just make one pixel fixtures instead of bars, and place your fixtures where you want ...

also, if the fixture filtering is disabled, the fixture will sample single pixels at the center of each cell,
allowing you to effectively have "not active" image space in between pixels.

Wow, this option is a very hard work!
Recently I've been worked in a theater where their led system works with Protopixel's software & hardware and this allows to design bars with more defined nodes and a preview of the general composition that simulates the result of the different LEDs. I think this would be a good option for madmapper!