More click events simpler

[ethereumdegen]

This builds off of @TheTacBanana 's pr #275 . It offers the same functionality as that one (and uses much of the code of that pr) but executes it in a slightly more streamlined design by not changing the EventType enum at all but instead simply adding a 'button' enum to the CursorEvent struct.

This means the examples dont need to change and existing user code doesnt break and you can still detect which mouse button has been pressed by reading the struct.

#[derive( Debug, Copy, Clone, PartialEq)] pub struct CursorEvent { pub pressed: bool, pub just_pressed: bool, pub just_released: bool, pub position: (f32, f32), pub mouse_button: MouseButton // new }

[TheTacBanana]

Definitely agree that this is the better and simpler approach compared to mine, I extended your approach a bit to support any number of mouse buttons rather than being limited to just Left, Right & Middle. Also removes a bunch of the duplicated code.

https://github.com/TheTacBanana/kayak_ui/tree/n-mouse-button-support

Although might be taking it a bit far, not sure if anyone will ever want to detect when their forward button has been clicked on an element.