With OpenLayers and MG OS >= 2.1, with GETDYNAMICOVERLAYIMAGE, setting <b>useOverlay</b>=true in map options, and <b>useAsyncOverlay</b>=true in map params, <br>showLayers/hideLayers is the same as GETMAPIMAGE.<br><br>The thing I always forget is where to set useOverlay and where useAsyncOverlay.<br>
If using overlay, in params must be set BEHAVIOR = 2 [I use 3 or 7] otherwise ovelay don't work [this was hard to find!]: <a href="http://trac.osgeo.org/mapguide/wiki/MapGuideRfc38">http://trac.osgeo.org/mapguide/wiki/MapGuideRfc38</a> <br>
<br><br>For MG OS <=2.0.2 you cannot use useAsyncOverlay, ovelays are synchronous, and, in my advise, should not be used [the request is blocking].<br><br>Regards,<br> Pietro Ianniello<br>