all the forms on mobile devices fit perfectly on the screen, if you swipe left/try to scroll right, nothing happens as the form fits withing the display size..
but there's one form, no different from the others, that if you swipe the form scrolls horizontally and there's a large blank area to the right of the screen, which is causing alert boxes to not fit correctly due to them thinking that the form is that wide, so the dialog boxes render wider that the screen. its as if the mobile device is seeing the form as in "desktop" version
You better check the HTML source in the desktop version, there may be some extra content (e.g. added by some server event such as Page_Render) in the page making the page wider than you expected. When you "swipe", you actually scroll (the scrollbar not visible in mobile browser) right so you see the blank content.
I think you're correct, just took another look at the app, and i do have a bootstrap panel on the top to display notes to the user, suspecting its not resizing to the screen width causing the additional blank width..