I always assume the user can change the size of the browser window, and try to ommit using fixed width or height. Some standard layout components are not well suited for this. I chose to expand some components like the standard box so it can be used with css properties such as width: 100%;. This leaves all of the sizing to the browser.
It seems like you are trying to build a menu with a dojo accordeon container. To accomplish this I used a dojo tree component, which does not put me in a position where I have to determine the height of the window, and manually resize when the users changes the browser window size. (see attachment).
I have used widget.getpixelheight for some small components, but I do believe that is bad practice and will provide a lot of work in the future if you use this for your entire web application.
Generally speaking, there are not many websites around that use a page that fits the browser's height.
Kind regards,
Bram
Bram_Callewaert