scroll-bug or feature?

[Wim Huls]

Just wondering: is this behaviour intended?

Scenario:
Open a page, witch is long enough to get a scrollbar;
Push the left mouse button while mouse on the slide;
Move the mouse-pointer out of the browser window;
Click with the right mouse button;
Release the left mouse button;
Move the mouse pointer again into the browser window.
Now you can scroll without pushing any mouse button.