Get last active window: Get Previously active window

Question

I am working on an application which needs to get the last active window handle. Suppose my application is running then I want to get last active window handle that was just pre

Answer 1

This is similar to alternate SO question, I would assume you would just track the active window and upon change you would then know the previously active

Edit, this is basically code copied from the question I linked that was looking for current active window but with logic to persist the lastHandle and identify when you have a new lastHandle. It's not a proven, compilable implementation:

[DllImport("user32.dll")]
  static extern IntPtr GetForegroundWindow();

static IntPtr lastHandle = IntPtr.Zero;

//This will be called by your logic on when to check, I'm assuming you are using a Timer or similar technique.
IntPtr GetLastActive()
{
  IntPtr curHandle = GetForeGroundWindow();
  IntPtr retHandle = IntPtr.Zero;

  if(curHandle != lastHandle)
  {
    //Keep previous for our check
    retHandle = lastHandle;

    //Always set last 
    lastHandle = curHandle;

    if(retHandle != IntPtr.Zero)
      return retHandle;
  }
}