with a lot of icons on the same url bar, it's hard to find a window drag handle, a fundamental flaw in Windows -not the only one! One does not usually "read" the full url; so, its width doesn't matter unless you want to paste or edit the url.
Shouldn't you be grabbing the window from the titlebar to move it? As well as the reserved space on the left and right of the tab bar. Unless something in that regard has changed since I last used Windows... early 10.
The idea in general sounds good but I don't feel like restricting viewability of the URL bar is needed (or welcome, as obscuring or removing parts of the URL has caused issues in the past and is a privacy and security threat). That said, between the URL bar and the tabs bar there's enough space to grab a window (lots more than having to grab it by the borders to resize, for example).
Would having a dedicated control one can place in the tab bar or URL bar to be "grabbable space" be useful? Not ony it would allow us to place wherever we feel it more comfortable, but it would also automatically restrict the size of the URL bar where needed, as does placing the sidebar or pocket buttons.