Window vs ChildWindows: When whould I use which and why? about imgui HOT 4 OPEN

As the name suggests, a child window needs to be a child of something, it is always embedded in a window or recursively in another child window. You cannot use child windows without using windows first.

Windows are the things you can move around with their title bar, dock whereever you want, close with an X button, ..., usually at least, There are ways to change some behavior, but that's not relevant for a basic understanding.

Child windows are embedded regions within a window. In a classic file explorer window, you can think of the directory view (tree view with hierarchically listed directories) as a child window. The file list (list of files contained in the currently selected directory) then is another child window. They are part of their parent window and cannot be independently moved, docked or closed, but they can be scrolled independently (if they have enough content to need a scroll bar).

When to use what is more of a UI design question, this concept is not specific to ImGui. Automatic resizing can be used on both windows and child windows, but whether to use it or not is a UI design question again.

from imgui.

Very simple example :)

This entire page you are reading now is the Main Imgui window.

A message, for example, my comment that you are reading now, can be drawn in a child window (which is located in the main window), that is, the frame in which the comment is located is a child window, and if my comment does not fit vertically, for example, the child window will create a stripe itself scrolling for example. And so on.

from imgui.

They are part of their parent window and cannot be independently moved, docked or closed,

Does this means that I can only use docking with windows?

Thanks a lot for the answer.

from imgui.

Internally they are more or less the same. A child window is a window that is embedded in another window, while a normal window has decorations like a title bar. You can even argue that a docked window becomes a child of its dock host. But an actual child window cannot be docked, it would need to be ripped out of its parent window for that and thus cease to be a child window.

from imgui.