Draw a square around an address on a google maps type map

[Pierre45]

Hello everyone,
I just discovered BAS and I'm delighted. I want to automate data entry on a site that contains a google maps type map. I want to draw around a point (an address that I enter with GPS coordinates.) a square of 50m x 50m.

But I can't position, center the map on the screen to do the tracing.
the scale of the map sings in the site of origin and the display of BAS

When I zoom on the map, the address shifts from the center of the screen. Also,
I can't make the link between the GPS coordinates of the map and the coordinates of the BAS window.

Can someone help me solve this first problem.

Thanks in advance.

Pierre