Magento - Preloading all Product Categories list when editing a product
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In the Admin / Edit Product / Categories section each subcategories is loaded by pressing the + symbol (this uses an AJAX call to get the subcategories) with is very slow for multi level categories (eg pressing 3 to 5 + symbols).

Is there a way (php or other) to have all the categories and subcategories (all levels) listed by default. 
