Without this change, window buttons would get stuck in the "pressed"
state as long as the left mouse button was pressed, even if you moved
the mouse cursor out of the button rect.
This ignores unhandled mouse clicks for the window buttons. Right now
right-clicking on the window buttons animates them as if some action
were to occur when the mouse button is released.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
Button now can handle middle and right clicks.
Added 2 new handlers in button class: on_right_click for Right mouse
button and on_middle_click for middle mouse button.
Added functionality to vertically maximize window with middle mouse
click on the maximize window button.
Also added a way to vertically maximize window by resizing window
height-wise lower than the maximum window height.
