Toggles between zoom modes: normal, fit to width, fit to window
目前為 2016-01-31 提交的版本，檢視 最新版本。
這裡只顯示彼此間有代碼差異的版本。 顯示所有版本。
Fixed weird behavior in Firefox. Apparently it too now needs a stopPropagation :/
What the fuck, Mozilla? In Firefox 96, document.body.clientHeight always is 0 for pictures. Fixed by using a different source for height.
