Here is the Docked mode option for "Preview" window.
I removed the docked mode i.e. undocked it. And here is what I got.
There is no more "Docked Mode" option. Now I cannot properly work with designing layouts. Preview automatically hides when I change anything in the layout.
Here is the simple solution for reverting to "Docked Mode".
- Select the Preview Window
- Go to Window menu > Active Tool Window
There you go. The Preview window is in Docked Mode. And there is the option for Docked Mode again.
Option 1
First open any layout file to set the preview as active window. Then as the first answer says, goto Window in menu > Active Tool Window > Select Pinned Mode, Docked Mode and Split Mode
Option 2
Open a layout file. If the preview window doesn't appear, first make it visible by clicking View in menu > Tool Windows > Preview. Now preview window will appear. Then right click on the Toolbar in the preview window itself (the one with blue color)
to show a list of options. Then there, select Pinned Mode, Docked Mode and Split Mode
Regards.
The first answer is right, but you must first click Preview Window. Then you go to Window menu > Active Tool Window, choose Docked Window and Pinned Mode.
Here is the simple solution for reverting to "Docked Mode" preview:
Go to Window menu > Active Tool Window>Docked Mode(true).
It didn't worked for me , But helped me ,Thank you.
Another Solution is 1.Select Preview window(Focus on it) 2.Unselect Floating mode and Pinned mode 3.goto Window -> Active Tool Window -> 4.Unselect Floating mode and Pinned mode 5.Now you can see Docked window option here(Window -> Active Tool Window ->) 6.Select Docked Window
If pin mode and docked mode options in window are in a gray color, then First, go to window-> restore default layout-> again go to window->active tool window, pin mode and docked mode options will automatically made visible, so that we can select(or tick) them.
来源：https://stackoverflow.com/questions/30160081/no-docked-mode-option-in-preview-settings-in-android-studio-once-undocked