This directly adress the issues caused by rB536c2e0ec916.
Since the state tracking is done at a lower level, using the bgl
functions needs to be safegarded by the state manager.
The current workaround is to bypass `apply_state` when inside a
callback that used a `bgl` function.
Related to T80730.
This fix T81003.
Also this fix the default blend equation for callbacks.
Fixes T80169 T81289.
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