debugSymmetricPaintCount property

The number of times that this render object repainted at the same time as its parent. Repaint boundaries are only useful when the parent and child paint at different times. When both paint at the same time, the repaint boundary is redundant, and may be actually making performance worse.

Only valid when asserts are enabled. In release builds, always returns zero.

Can be reset using debugResetMetrics. See debugAsymmetricPaintCount for the corresponding count of times where only the parent or only the child painted.