I wrote a little download manager in python, and now i want to "catch" downloads from Chrome Firefox and Explorer so they will download with it, instead of each built-in download manager of the browser itself.
I want to know when each of the browsers are starting a file download, so i can prevent the default behavior and use my own manager. All i need to start a download myself is the file url of course. 
I know that in the past there were popular download managers such as "Get Right" that did exactly this. I want to do something similar.
Any ideas how would i go about doing this?
Each of the web browsers e.g. Firefox, Chrome, IE, Safari, all have plugin models.  If you are going to truly integrate your manager into the web browsers, you will need to examine their plugin models, and make your download manager work through that.
Catch downloads from Chrome/Firefox/Explorer with python