add property isOnTop to Layer

[elemoine]

Add property isOnTop to OpenLayers.Layer. Layers with the isOnTop property set are always above (z-index) layers that don't have this property set. That property has no effect for baselayers.

This is useful for example when you want to add a vector layer once for good at init time, and be assured that this vector layer will always be above other overlays that you may add and remove afterwards as the application goes.

I have tried different paths to implement this. The best and simplest code I've come up with up to now involves adding a new Z_BASE_INDEX category, namely OverLayTop. Do you see any problem with adding this to the Z_BASE_INDEX object?

Patch to come, once the unit tests are complete.

[crschmidt]

In general, I don't have a problem with the idea of having a secondary layer of overlays. I think that we may want to think up a better name, but I don't know one off the top of my head.

[euzuro]

is this still something we're thinking of doing?

to me, this sounds like 3.0 material. i'm bumping it to there. please move elsewhere if you feel strongly.

[elemoine]

I'm totally fine with bumping this to 3.0, where we may reconsider the baselayer/overlay thing.