My mouse have "side buttons" like this image:

In VSCode and browsers it has the same effect as Alt+Left and Alt+Right key bindings, which goes to previous/next page.
However, in Zeal, clicking this button will cause Zeal to go front/back twice. When pressing down side button, Zeal goes front/back. When releasing side button, Zeal goes front/back again.
Expected behaviour is to only go front/back once in the process of pressing down and releasing side button, as VSCode and browsers do.