https://docs.unity3d.com/6000.4/Documentation/ScriptReference/IMGUI.Controls.TreeViewItem.html
Unity - Scripting API: TreeViewItem
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https://docs.unity3d.com/ScriptReference/IMGUI.Controls.TreeViewItem_1-children.html
Unity - Scripting API: IMGUI.Controls.TreeViewItem_1.children
scripting apiunityimguicontrolschildren
https://docs.unity3d.com/ScriptReference/IMGUI.Controls.TreeViewItem_1-hasChildren.html
Unity - Scripting API: IMGUI.Controls.TreeViewItem_1.hasChildren
scripting apiunityimguicontrols