Welcome to the forum!
For Windows, and for the current version of Inkscape, it's not easy to get a different theme color (dark gray). However, in the upcoming version 1.0, it will be easy to do. I guess 1.0 should be out within approx a year, more or less, very ballpark estimate.
For the sake of those of us who don't use key shortcuts, just for future reference, please say the name of the dialog or command, or whatever it is.
Let's see.... Shift + Ctrl + a is.... Aha, Align and Distribute. Shift + Ctrl + f is Fill and Stroke dialog.
So most....I think almost all dialogs can now be docked. But when you say "stacked", I think you might be talking about a particular arrangment of docked dialogs. Unfortunately, it's not only tricky to make it work, it's hard to explain.
I can make a quick video to show you some controls, and then you can play around with it, to try to make it work. I don't have a lot of luck with it. But maybe you will? Or maybe someone else can explain.
By the way, you can find tons of Inkscape tutorials listed on the home tab of this website. Nick's are only a small part of all that are available.
I'll be back with the video shortly.