How does one go about fixing its location on the screen? I would like to have the window open at the lower left, for example.
The screen shot is from a familiar template -- a modified version of "basic viewer" that implements esri/infoWindowBase and its subclass, infoWindow.
The application honors popup settings for a map created in ArcGIS Online. I don't mind scribbling some JavaScript to address this--
the answer in this case was to modify "styles.css." The general method was to run the app, find the element added at runtime to the document (as libraries are loaded) and write some css code to address the issue. The application in this case is honoring settings in an ArcGIS Online map, and (for example) "esriPopup .outerPointer" is discoverable by inspecting the browsers' consoles at run time. This is admittedly a hack, but it works.