Commit 58ba1a73

add proper texture support for widgets

Does exactly what it says. But also, it adds a “cancel” button in the context container that calls the generic “cancel” function in the MainApp class, which is also triggered by pressing ESC. The behaviour of the function depends on the current game state. To name an example, in the simulation mode it unselects the currently selected object.

Commit 853f95df

flesh out the container system and add add some non-dummy callbacks to the mode buttons

This introduces a concept of “dirtiness” to the widgets, if a widget is nor marked as dirty, no longer recalculate its hash value on every render cycle.
The latter part of the commit message is a bit misleading, as it merely restructures the way the game mode is changed, not the fact that is changed.