WordPress at a glance
action is not described

customize_render_panel action-hook . WP 4.0.0

Fires before rendering a Customizer panel.

Usage

add_action( 'customize_render_panel', 'action_function_name_1490' );
function action_function_name_1490( $this ){
	// action...
}
$this(WP_Customize_Panel)
WP_Customize_Panel instance.

Where the hook is called

WP_Customize_Panel::maybe_render()
customize_render_panel
wp-includes/class-wp-customize-panel.php 268
do_action( 'customize_render_panel', $this );

Where the hook is used (in WP core)

Does not used.