1. Will look into config issues when migrating from 10.12.
2. This is a bug. It should shrink to (
not including borders / title bar) 960x600 in this example (formula is still highest multiple of 320x200 that fits on screen). However, there is a way to enlarge it: click and drag on the borders, like with any program.
(If this isn't working, that would be a bug.)
3. The skill bar's zoom is not tied to the level area's zoom completely. Even if you adjust the zoom lower via in-game zooming, the skill bar will never shrink below what you've set as your zoom setting. And the skill bar won't be zoomed to a larger size than can fit in the window. (In the case that these conflict, the "won't be larger than..." rule has priority, for obvious reasons.) If you're using a 960x600 window, there is not enough space to fit the skill panel at a 3x zoom. Your window would need to be at least 1248px wide, and at least a certain value which I don't remember exactly tall (120 + a certain amount more to display at least
some level area, I don't remember what I set the minimum as).
Black borders, this means the skill panel + level, at the current zoom settings, isn't enough to cover the full available space. There is an option - which should be on by default, can be turned off, but looks like I may have forgotten to actually have written to the INI file so in current exp you'd have to turn it off again each time - that will, at the start of a level, set the zoom such that it's as high as possible
without any vertical scrolling, with the exception that this setting will not set a zoom lower than the one you have configured in the config menu (you can still manually in-game-zoom out further, of course). However, with the setup you've got, zooming the level area (I'm assuming a level with a height of 160px here) to 4x would result in vertical scrolling, but zooming it to 3x does not
completely fill the screen area. Discussion with someone else (IIRC, IchoTolot) lead to the decision to prefer black borders over vertical scrolling for this setting, as well as to only pay attention to whether
vertical scrolling will be involved rather than both directions.
Smooth resampling - this depends on how powerful your PC is, which is also why there's an option to turn it off. On mine, the slowdown is only just noticable. Around the time I added the smooth resampling, I also modified the fade code to try and improve performance (at the cost of a slight bit of quality). I have an idea on how I might be able to improve this, which should help.
Music volume - because the new version tracks "what volume should the music play at" and "is the music on or off" seperately, although the settings aren't exposed as seperate ones in the config menu. In memory - and in the INI file - however, these options are seperate. This is so that, for example, if you turn music off in-game then turn it back on, the volume stays the same, without the need for a seperate "stored volume" variable.