I've just tried adding the esri/dijit/Measurement widget to a web map application. It works fine when the map is using a Web Mercator projection, for example when used with the ESRI base maps. However, when I instead load our own maps which are in ED50 / UTM zone 31N (sref: 23031) the measurement widget does not appear to work correctly.
Firstly, when using the area tool, you can draw an area on screen as expected. When you double-click to end drawing, while previously it would then have calculated and displayed the area, nothing is displayed. However, I can see that it does at this point make a call to the geometry service (which it doesn't do when using Web Mercator) and the geometry service replies with a length and area. It therefore appears to be doing the work, but the result is just not displayed.
Secondly, and I might just be confused here, but the length and location measure tools both work in the same way as they did when used with a Web Mercator map in that the length tool immediately calculates and displays the measured length while you click and the location tool immediately displays the lat and lon of the mouse position in degrees or DMS as you move around. Both without making a call to the geometry service which I thought should be required because of the map not being in Web Mercator.
Has anyone else had either of these issues. Does anyone know how to go about fixing or logging a support call with ESRI?