Yes, you're right - we did make a large change to the way the white marker works.
In 2.11, a white marker works more like a water pen, than the previous markers did. We were concerned that the previous versions of the marker weren't really like a marker pen. The current one more closely models what real-world marker pens would do.
In general, when we do upgrades, we try not to change too dramatically the way any tools work as artists get to know a tool and how it works.
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"