When clicking on the button, the adwaita theme makes a short animation to show that the button is pressed down. Is it possible to remove this animation? It makes it harder to confirm the button is pushed in the first moment.
I'm not sure this is on-topic for SU, but anyway.
This transition animation for
GtkButton, like most others, is controlled by the Adwaita theme CSS. It therefore can be overridden by providing your own customised theme (or if you're the only user, you could just edit the relevant CSS file in place).
(Alternatively, I'm not sure, but it might be possible to alter the
GtkStyleContext somehow to override the relevant property within a program. However, I can only see how to add a class immediately, not alter properties of the CSS itself. So maybe not...)
Anyway, you would want to find nodes named starting
button, and there you'd need to alter the property
transition. As of now, the transition duration for
Other widgets' animations can also be controlled by the property (surprise)
animation, so make sure you search for both in that case.
(I know because I needed to sync a different animation to the button transition, and I found this thread on my way.)