Control glyph order

There needs to be a way to control the vertical stacking of glyphs. They are not displayed in the order they are created. The lack of Z-order control means I cannot do something as simple as displaying a line glyph on top of a BoxAnnotation. Instead I have to resort to using certain colors and alpha values.

I think other annotations are impacted too. For example, how do I constrain a Label to only appear within the plot window? I haven’t figured this out and am guessing it’s related to the display layers.

Yes, I’ve read #696 and it shouldn’t have been closed. This commit is the only one I see related to Z order and it did not expose control the user.

[dubreuia]

Ok found it, the renderer is the thing returned by BoxAnnotation or quad, so for future reference:

box = BoxAnnotation(...)
box.level = 'underlay'

[bryevdv]

By default, annotations render on top of glyphs, since that is the more common use-case. If you’d like to put them in a different render level, you can set a different render level for them:

http://bokeh.pydata.org/en/latest/docs/reference/models/renderers.html#bokeh.models.renderers.Renderer.level

http://bokeh.pydata.org/en/latest/docs/reference/core/enums.html#bokeh.core.enums.RenderLevel

e.g. all 'underlay' renderers are rendered before all 'glyph' level renderers.

Among the renderers in a given render level (e.g. glyphs) things are rendered in the order they are added.