Load Plugin error

[butler]

Load Plugin is used to force an update of plugin models that may have changed but somehow not triggered an auto update. This works fine if the category at the time is not Plugin Model. However if it is "Plugin Model" and a plugin is selected on the fit page, load will clear the model dropdown box, but does not clear the rest of the model GUI stuff on the fit page. Strangely, if the model that had been chosen is a new style plugin and the user then tries to change a parameter and run the model everything behaves though the model dropdown remains blank (suggesting no model is currently "active" for that fit page. However, doing the same thing with an old style plugin causes an error that throws a rather unhelpful error message suggesting a thread problem along with a more useful error that the parameter being modified does not exist.

2017-02-26 11:30:47 : Traceback (most recent call last):
File "C:\Users\Paul\git\sasview_new\src\sas\sascalc\data_util\calcthread.py", line 268, in _run
    self.compute(*args, **kwargs)
AttributeError: 'NoneType' object has no attribute 'pow'

2017-02-26 11:30:47 : Traceback (most recent call last):
File "C:\Users\Paul\git\sasview_new\src\sas\sascalc\data_util\calcthread.py", line 268, in _run
    self.compute(*args, **kwargs)
AttributeError: 'NoneType' object has no attribute 'pow'

Not sure why this does not also throw an error with new style models but if it is going to work the drop down should not be blank.

Possible solutions:

1. Rather than reset the selected model of Plugin Model, the code could reload whatever model had been selected and keep that model in the dropdown.
2. Finish the reset operation. Basically this is behaving similarly to changing category which clears the model selection box AND clears all the model GUI elements on the page. So just finish the job and clear out all those elements.