In the control tree, the right mouse button firing selection, thus, when I click to select multiple items, and click the right mouse button to display a popup, you lose the selection this items.

Fix is simple: add a check to see if the primary mouse button is the one responsible for the event, and only perform selection in this case. Despite patch file looking big, it is mostly due to indentation of existing code, and only the addition of three 'if' statements.