https://bugs.winehq.org/show_bug.cgi?id=43093
--- Comment #5 from Zebediah Figura z.figura12@gmail.com --- Most of the problems have been due to the lack of an implementation of MSI's "external UI", which is a series of messages that MSI should be sending to a given application callback function. I've been submitting several patches to implement this, with visible results. Currently, with 2.12, it's possible to immediately cancel out of the application, without triggering a hang. It's not yet possible to install the application—it currently gets stuck on "Moving files"—but it's a start.
Currently, the presence or absence of the staged patch—though as far as I can tell it *is* correct, as the tests Sebastian added show—does not actually affect the functionality.
There is a (rather amusing) bug in which pressing cancel does not immediately spawn the cancel dialog, but rather first spawns a dialog prompting the user to choose a file. Closing this and pressing cancel again brings up the cancel dialog as expected. This seems to be caused by the installer incorrectly setting _BrowseProperty. This was introduced by commit 166a7e993cb0033fac7ec2712c346558fb7bd100 which was introduced to fix bug 28219. In all likelihood the property needs to be set only at a specific point.