Can I change the properties of a different running program?

In short im wondering if there is a way to change the display properties of a Windows 开发者_StackOverflow社区form, from a different program.

For instance, lets say I have two applications running (A and B respectively), Program A has a button that says 'Re-size Program B'. My question is, is there any way when that button is pressed in program A, I can access program B in memory and change its forms Width and Height properties (or any properties for that matter)?

I don't necessarily need source code, (if this is even possible- it would be very much appreciated), mainly I am just curious of such a thing is possible (in any language/IDE)- then I can sink my time into learning how to implement this concept.

My guess- for obvious security reasons, would be no... but its better to ask a dumb question than assume a dumb answer, if you ask me.

Thanks kindly for your time on this issue

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Got it for the Window Size, how about for properties like 'TopMost'?

Thanks again,

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Simply wonderful thank you all for your great help!

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You can resize other programs' windows by sending system messages into them. It is done by WinAPI function

LRESULT WINAPI SendMessage(
  __in  HWND hWnd,
  __in  UINT Msg,
  __in  WPARAM wParam,
  __in  LPARAM lParam
);

First parameter is a handle of target window. You can get it with other API functions (like FindWindow).

Second is message code - in your case it's WM_SIZE.

The last two parameters are described here http://msdn.microsoft.com/en-us/library/ms632646(v=vs.85).aspx

This is for C++ WinAPI. In .NET you can use P-Invoke to call WinAPI functions. Declarations for P-Invoke can be found at http://www.pinvoke.net/

UPD: There are other functions that fit better for this: SetWindowPos and MoveWindow

This is example for resizing. For other things that you can do, see this MSDN section

http://msdn.microsoft.com/en-us/library/ff468919(v=VS.85).aspx

Most controls inside window (buttons etc..) are windows too. You can get their handles and control them in same way

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If the window is already open and your code can find it then it can resize it. For instance, the code to arrange windows when you right-click on an empty area of the taskbar does this.