Umbrella24 in short control nodes capture mouse events. so if your code is in the deepest level of the node and the node is transparent or something, or the top node has some color or somehitng is not transparent, then the signal is captured by the top level node, not the deepest level.. in order to getaway with this, you either need to cycle through all the nodes in your mouse event when you click, in the mouseevent input object, or use the ui in ever top level node to set the filtering for mouse..
the documentation explains a lot of things but not specific.. imagin it like this, it explain what is peanutbutter and how to use it, and it explains what is bread and how to use it, but it dont explain that you can make peanutbutter sandwich..