How can I find the absolute coordinates in pixels of a certain cell?

I am developing an Office 2010 addon (the Ribbon UI) and I add a new button to a new menu in the Ribbon and when the button is pressed, I want to get the screen position of that cell. The problem is that 

```
Globals.ThisWorkbook.Application.ActiveCell . Top / Left

```

only give the position relative to the `A1` corner of the spreadsheet, while I want the position relative to 0,0 of the screen.

I found this: [How to get screen X and Y of an Excel 2003 cell in C#](https://stackoverflow.com/questions/6283084/how-to-get-screen-x-and-y-of-an-excel-2003-cell-in-c-sharp) but it's for Office 2003 and I don't fully understand the answer.

I'm using C# for devel, but VB will also do.

Thanks!