I am getting this same behavior. The Attribute Editor for my EditorWidget is freezing up on me and locking down the application. This tends to happen when I try to edit attributes quickly, but that's not always the case.
My Attribute Window isn't very large, but I do have several fields that are connected to large domains. (i.e. a list of all valid street names in the city) However, it still freezes sometimes when I'm not editing those fields.
Here's my basic setup: I've got a tiled basemap, the Infrastructure Map Service (Dynamic), and a Feature Layer for every feature class in the Infrastructure Map Service (there are 15 total). The Feature Layers default Where Clause is "OBJECTID = 0" to prevent them from all drawing while zoomed out. Instead, the Map Service is used to show the features. After zooming in close enough, (in this case, a resolution of 5.0) the Map Service turns off and the Feature Layers turn on. I also have a ComboBox that contains a list of the Feature Layers. None of the Feature Layers are visible until I select one from the ComboBox, then that FeatureLayer's Where Clause is set to "REMOVED IS NULL" (REMOVED is an attribute that we populate instead of deleting so we can recover accidentally 'deleted' data).
Other than that, it's pretty much exactly the same as the first sample for the EditorWidget. I've checked the log files and added every event handler I could find and none of them can explain what's going on or why the Attribute Editor is freezing up.
