Julian Eisel
f1df685f57
Uses a inheritance based approach for querying warning of tree elements and the mode column support of display modes. For the warnings, tree elements can override the `AbstractTreeElement::getWarning()` method and return a warning string. The UI will draw the warning column with warning icons. This makes the warning column more generalized and easier to extend to more use-cases. E.g. library override elements will use this after a followup commit. To support mode toggles a display mode can now just return true in the `AbstractTreeDisplay::supportsModeColumn()` method. This makes it trivial to add mode columns to other display modes, and less error prone because there's no need to hunt down a bunch of display mode checks in different places.