How to debug juce::NSViewComponentPeer::drawRect

Is it possible to find out how the rectangle size in juce::NSViewComponentPeer::drawRect (NSRect r) is calculated?

I am running into a very mysterious behavior - given there are 2 child views under the same parent view. Child view A is constantly repainting itself by a timer. By default, NSViewComponentPeer::drawRect is called with the Rectangle size exactly matching child view A. But when I add another child view C into the system, the drawRect is called with the width equivalent to the width of Child A + C, even though they do not overlap. This is causing unnecessary repaint of child C and is an performance issue in the long run. Any suggestions on how to debug this would be very appreciated!