I am building an app, which will draw a representation of column-based data. I need both interactable cells and headers, so instead of adding suppplementary views for each column, I made another NSCollectionView that contains headers only. The issue is that I would like to share selection rectangle state between these collection views, but I am not sure if there's some good way to achieve that or I have to hack whole controller.
Initially I was thinking about making an overlay on whole window, that would register in first responder chain, but it would use methods like draggedMouse only in my own methods and I would override built-in to pass the events to views behind, then if the view detected that user would like to draw a selection rectangle (select multiple items), that event would be moved to overlay view.
I thought also about making first row of items as sections (I am using compositional collection view layout, so it isn't that hard), but I think it would make features like drag and drop a huge pain in the bottom.
On the image you can see part of these collection views and how it looks now.
