I tested multiple versions of the MPC today.
In M6 [1] the D&D feature didn't work today and
threw some exceptions that I didn't investigate. It could
have been anything, e.g. a change in the web services API,
and I wouldn't use this version to draw any conclusions.
M7 [2] shows the same behaviour as the RC builds and the
final build of the packages. In all cases, the Finish and
the Confirm button stay disabled initially. This is in
line with the code change that caused this and had been
pushed to Git 3 months ago.
My first conclusion is that the D&D feature isn't
popular, otherwise this glitch had been detected earlier.
This is no wonder because (a) D&D isn't used very
often from web pages to applications, and (b) it is much
easier to use the MPC client itself to look for new
plug-ins and to install it directly from there. That's
workaround number 1: Use the MPC itself. It has been
working perfectly in all of my tests.
And what will a user do when the buttons are disabled? The
chance is really high that in this case he or she will try
to disable/enable one of the checkboxes which solves the
problem by triggering an update to the buttons. That's
workaround number 2.
And we shouldn't forget that SR1 is only 3 months away, that's
about the duration that this bug exists. If this is too long
there are other low-risk options, too, that can be discussed.