I have just removed adapta, I see the incompatibility now as certain apps were looking horrible. Thanks for the very thorough education on the subject. I now understand just how complex these themes are. Oh, and I happen to love the "pop" theme as well, so it would be nice if these themes could be incorporated into MX in the future.
Adapta and Pop themes are already in the MX17 repos, even though MX17 is still some ways from being released. However, the dark variants all look so much better than the light themes. The reason is that in the light variants, the XFCE panel and whisker menu show up as a blinding bleached white. It's almost painful in its whiteness. You could change your panel settings to set it to a fixed darker colour instead of having it follow the gtk theme, but I'm not sure how to do that for whisker menu.
Of course, if you knew how to tweak the files in the Adapta/Pop light themes to set dark panels/whisker, that would be great.
As for the dark themes, while they show up quite nicely, a lot of impressive animated effects you see in gtk3 desktop environments are lost because XFCE is still a gtk2 desktop at the moment, at least in Debian Jessie and Stretch.
Like Stevo said, we were discussing this in the Dev Team forum, and these were some of my observations about Adapta in XFCE:
Re: dark theme -
1. It's very cool, I love the strong colours, and it's great on Gnome, Cinnamon and Budgie (gtk3) desktops, but it might not have the most visible/identifiable GUI elements in XFCE (gtk2). For instance, in gtk2, you don't have a lot of the mouseover and animated effects you have in gtk3. So a lot of the visual cues are lost, making GUI elements less visible.
2. Look at tabs in Thunar (gtk2). Other dark themes have properly visible outlines for things like active tabs. In Adapta-Nokto, it's so dark you wouldn't know there is a tab if not for the neon blue indicator light below the tab text. If you mouseovered a tab in Nautilus or Nemo file managers (gtk3 apps), the tab would "light up" but not in Thunar.
3. In gtk3 apps, when you click on a tab, a "ripple" of light goes through the tab. You don't get that in a gtk2 app.
4. Same with mousing over items in a folder in Nautilus/Nemo. You don't get that in Thunar or any other gtk2 app.
5. you can compare the difference in MX:
- galculator and Archive manager are gtk3 apps. Open the Preferences dialogue window for these 2 and mouseover all the GUI elements
- do the same with Thunar, any of the other XFCE applications.