The inspector dock supports custom plugins to create your own widgets for editing properties. This tutorial explains how to use the class_EditorInspectorPlugin and class_EditorProperty classes to write such plugins with the example of creating a custom value editor.
To register these scripts as a new editor plugin, you have to create a
plugin.cfg file as described in Making plugins.
We start by creating a script extending the class_EditorInspectorPlugin class. This is needed to initialize the plugin and add the custom property editor that we'll later define.
Next, we define the actual class_EditorProperty custom value editor that we want instantiated to edit integers. This is a custom class_Control and we can add any kinds of additional nodes to make advanced widgets to embed in the inspector.