How to execute some code everytime an application window (other processes) is opening?

Question

I am trying to track visible windows from all currently running processes. My program interacts with these windows and the faster it can detect them the better. My goal is to move visible windows to a certain location on screen before they even draw in the default position if that is possible. If not I want to move them as quickly as possible after they are created.

Right now I enumerate through the visble windows using EnumWindows (p/invoked from user32.dll) in a loop with as small a delay in between iterations as I can justify.

I am looking for a method to hook into 'something' which will allow me to wait for a 'window opening up' event to fire instead of constantly polling.

Are there any methods to achieve this?

Answer 1

You need the SetWindowsHookEx() API function, setting a WH_SHELL hook. The callback gets a HSHELL_WINDOWCREATED notification when a new toplevel window is created.

This is a global hook, you cannot write the code for this hook in C#. It requires a DLL that can be injected in a process, the CLR cannot be initialized properly to support managed code. You'll need an unmanaged DLL to get the job done, this project offers one.