Windower v4.2's hooking uses a very old x86 library known as madchook. For legal reasons, we haven't been able to update madchook since the creator took it private but did have permission from him to use the old version. In order to get around this, Iryoku wrote a new x86 hooking library for Windower v5 (a work in progress).
As it happens, the Creators Update for Windows 10 (roll-out began yesterday) breaks the old hooking library. However, through collaboration with users who downloaded the Creators Update early, we discovered that Windower v5's hooking library had no problems with the Creators Update.
In the last three days, Iryoku heroically backported v5's hooking library to v4 and adjusted everything for it (bumping the version to 4.3). Two nights ago we got it to build and Arcon has been bug squashing for the last day.
There is also a pretty good chance that this Windower update will also fix the compatibility the issues people have had with Windows 8+ and Windower. This extends to the Launcher, where we've switched to software rendering and expect the white screen issues people were having to be fixed.
v4.3 and the new Launcher are both currently on -dev. If you are having problems with the Creators Update and want to log back in, we recommend at least temporarily using -dev. To do this, duplicate your entire Windower directory, then download
this Launcher, replace your existing Windower.exe, and log in.
I will update this post when it goes live, but please try it on -dev or we're unlikely to find the last few bugs that are doubtlessly lurking.