Sizer is a very useful tool for sizing and positioning windows. It adds a right click menu to a window’s title bar where you can select one of multiple configured window sizes and positions. It also displays the current window size while you are resizing it by dragging its frame.
Now, why would somebody try to defeat the usability of this tool?
Because they can?
Google and Mozilla did exactly that: By moving the tab bar into the window title. In Chrome, Thunderbird and Firefox right clicking on the title bar no longer brigs up the Sizer menu. In Chrome at least clicking on the window frame still gets this menu. Both browsers also prevent the size display while dragging the frame which at least works for Thunderbird.
And now guess which windows I would like to use Sizer the most?
Some software developers should be shot, just so they don’t have a bad influence on others.
(Since nowadays it apparently is necessary to explicitly say that: No, I don’t want anybody to take this as an ecouragement to commit a felony or act of terror.)