Modifier keys for User Interface

For example how I would expect it to work with material creation:

• press the plus icon holding a modifier key to create a material slot with new material in it.
• The minus button could be used likewise to delete a slot with the material assigned to it (from the blendfile).
• Assign pressing the "+ new" button for creating a specified material template like alt+click for emission, ctrl + click for transparent and etc.

This kind of interaction with user interface could be very usefully propagated to many parts of blender, as already done for pie menus by different addon makers