Email page

Hello @STGrajewski and thank you for posting your question on our Xfinity Community forums!  

If you are using a web based email client such as the original Xfinity website client or the new Yahoo based client for comcast.net emails, the size of the panes for folders and messages is pre-defined based on screen resolution and are not typically adjustable individually, thouh you can 'hide' the folders pane (though I know that doesn't address your concern for keeping it visible at the same time.)

On most computers, you can use the 'Zoom' function of your browser window to shrink or expand the page, you can also go from a windowed view to a full screen view (depending on which browser you are using.) 

To use the zoom feature on most browsers, you can select the three dot (hamburger) menu in the upper right corner and scroll down to Zoom, reducing the percentage of resolution on the screen will give you more 'real estate' to work with, though the caveat is smaller fonts based on your screen resolution (on windows machines you can hold down the ctrl key and scroll your mouse wheel as well).  

... How  do I expand Compose section of email page while keeping folder panel visible. ...

On some systems (I'm using Firefox on a Windows desktop and using a mouse) the fine line between the folder pane and the rest of the webmail window can be dragged left and right.