I want to display a window as a sheet, which is perfectly running with the following code:
[NSApp beginSheet:mySheet
modalForWindow:myWindow
modalDelegate:nil
didEndSelector:NULL
contextInfo:NULL];
However, there is ONE LITTLE PROBLEM:
- I’m using an implementation of Chromium Tabs, and – for some reason probably related to the inner logic of Chromium Tabs – the sheet seems to appear somewhat LOWER than where I’d want it to be… (Perhaps that’s what is considered as the window “border”, but anyway…)

What’s wrong? How could I fix that?
Just found it :
In the window’s delegate, we implement
window:willPositionSheet:usingRect:like this