Use these links to test how Firefox loads this page with methods sites commonly used to launch a new window:
Link with target="_blank" — diverts to a new tab by default
Link with onclick="window.open()" (no features set) — diverts to a new tab by default
Link with onclick="window.open()" (width and height set to 800x600) — opens in a new window by default*
Firefox 45 seems to be scaling the pop-up window based on the resolution of the page from which the new window is launched. To understand how this impacts your window size, you can experiment with zoom on this page before clicking the third link above.
To force windows with features (third link) to launch in a new tab instead, you can make a change here:
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