IDE appearance in 3.10 beta

quick advisory for people working off the latest dev branches. the 3.10-beta1 is not out yet, but this issue will probably also affect it.

in the upgrade to Qt 5.7+, some linux users reported that the IDE stopped listening to native GTK+ themes and stuck with the default Qt Fusion theme on some desktop environments. this created some really gross color clashes with dark editor themes which have been fixed (thanks Luke!).

while fixing the color issues, we decided it was time to stop attempting to cater to native appearances on all OS’s and use the Fusion style on all platforms. this reduces the amount of work we need to do to make the IDE appear attractive for everyone and gives us an opportunity to give SC a more distinctive visual style.

the impact visible to users working off dev versions is that the IDE suddenly got uglier yesterday. it will, however, get better soon. thanks for your patience!