Not sure how easy this is, but a few ideas:
1. Allow the ability to set the width of the page while keeping the height maximized to the monitor window. Typically for development I am mostly concerned with how a page responds to the width.
2. When Chrome Developer tools are open, do the same as above and then expand the tool pane to remaining width of the monitor.
This way Chrome can always stay maximized in the monitor. Great tool by the way! ;)
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