button doesn't update animation when it is tapped with trackpad

[vayn]

Hi, I'm a beginner of gtk(-rs).

I modified basic.rs a little bit: add a click event to the button. The signal handler was triggered very well when I tapped (not clicked/pressed) the button with the trackpad of MacBook, BUT the animation of the button didn't update. If I didn't set the click event to the button, I might think Button can't be tapped in gtk.

[dependencies.gtk]
version = "0.5.0"
features = ["v3_10"]