查找显示鼠标指针的监视器/屏幕

I will start from beginning, I aw working on an application which will span over multiple monitors, each monitor will contain a single WPF window and these windows are controled using a single viewmodel class. now lets say i have a button on all the windows at 200,300 (x,y) and i want that this button should be responsible for a tool on same window, while all rest are responsible for the application. When i try to get current mouse position or last click position i get position relative to the current monitor , i.e. in this case 200,300, irrespective of in what screen i am on. I will start from beginning, I aw working on an