1. Do not make position an inout variable
The function is meant to return a range for a given position, not modify
a position. So it makes no conceptual sense to use an inout variable.
2. Pass the selected state as an out variable
Using a boolean return value - in particular in an interface full of
boolean return values - makes the return value intuitively feel like a
success/failure return. Using an out variable clarifies the usage.
3. Allow passing every position value
Define what happens when position >= list.n_items
4. Clarify the docs about how this function should behave
In particular, mention the case from point (3)
5. Add more tests
Again, (3) needs testing.
It is easy to emit wrong ::selection-changed signals,
and then bad things will usually happen later. Add
some sanity checks to gtk_selection_model_selection_changed
to make this easier to track down.
