This is the concept of constrained by dimensions or expressions.
The current design is weak here:
1, we don't have a constaint system;
2, there's no smart entities either(with some dynamic parameters/mathematical expressions);
3, there's no topological entities.
LCWulf wrote
I would also really like to see 'Smart Dimensions' or something similar implemented in LibreCAD. It is one of the best features of Solidworks and really speeds up the drawing process. For those unfamiliar with it, the big advantage over 'the ordinary way' of dimensioning is that you can go back at any time after object creation and edit the dimension, and the object size will change accordingly without having to delete the object and redraw.
Strongly support it as a feature of LibreCAD.