TreeView can assert (and crash) sometimes with an assertion. This assertion is made to not introduce twice the same element. Right now even if an element is introduced twice, the event is logged but will not crash NaroCAD.
Solver options are exposed from the main interface to be one click away. One other change is that (excluding this screenshot that was a development photo) is changed to be named Hinter. In this way I will not use erroneously interchangeably those two words.