gtk - "Assertion `cr != NULL' failed" when working with Cairo.context from different objects -


my program consists of 3 classes. gtk , cairo.context instantiated in 1 of them. other 2 classes work context, passing around , drawing stuff on it. however, when try launch program, error "assertion cr != null' failed" (cr cairo.context instance) or "assertionself != null' failed" every method of 2 secondary classes uses cairo.context, either assigning object's property or drawing on it. when had code in 1 single class, didn't have such problem. can reason it?

hard without short example isolates problem.

i see use of 'self' in error message. in vala want 'this'. i'm newb, hth.


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