Why is this UI using Vectors instead of the Layout Editor from Mythic ?

Vectors offers the creator of your UI to ship it for far more resolutions than the UI was actually built for.
You can freely choose the UI scale in the Mythic settings without destroying the UI even after installing.

How can I change my UI scale without messing up everything ?

Change your UI scale in the Mythic settings to your liking. Vectors will take care of the rest.

How do I select a window for editing ?

Open Vectors through typing "/vectors" in you chat input.
Hover over the window you want to edit and click on the popup or choose it directly from the Combobox.
If it says there is no data for the Window, let Vectors create it.

How do I move my stuff ?

→ How do I select a window for editing ?
Little red dots will show you where your window ist sticked on to.
Scroll down to edit the position through changing numbers or clicking the arrow buttons.
The Buttons with 2 Arrows as a symbol will move your window by exact 1 pixel on the screen.

How do I resize my stuff ?

→ How do I select a window for editing ?
Scroll down.
If the "Lock Scale" option is active, use the arrow buttons or directly edit the number to change the scale.

What does the "Lock Scale" option do ?

It defines if Vectors should control the scale of the window.