The Cairo issue has been harder to track down.  Several users have reported Cairo builds which fail to display stipples.  I gather Cairo is the default so this must be a sporadic failure.  Recently a user with identical builds on two different machines, with the precise same version of GTK3 and Cairo, found that one system shows stipples correctly, the other omits them entirely.  On the non-working system, compiling --without-cairo resolves this.

The build version in questions is: 

He's willing to test these systems.