Automatically add buttons to the toolbar when GHA is loaded?

How to automatically add buttons to the toolbar when gha is loaded?
I need to add two buttons to the toolbar. How should I write them in the gha project?
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This is a button added after GH is loaded, and it needs a GH_Commonent to be inserted into the current GHDocument. How to add it to the GHA project? Is it automatically added to the toolbar after loading the GHA file?