BlockCategoryDisplay: Refresh Block context when reusing

In the category display, blocks reused when switching the current
BlockCode node. When that happens, the BlockExtension needs to have its
context update so that it can provide options for the current BlockCode
node.

https://phabricator.endlessm.com/T35647

Author: dbnicholson

addons/block_code/ui/blocks/block/block.gd

@@ -88,6 +88,12 @@ func get_parameter_values() -> Dictionary:
 	return template_editor.get_parameter_values()
 
 
+## Use the current BlockEditorContext components
+func refresh_context():
+	if _context and _block_extension:
+		_block_extension.context_node = _context.parent_node
+
+
 func _update_template_editor():
 	if template_editor == null:
 		return

addons/block_code/ui/picker/categories/block_category_display.gd

@@ -70,5 +70,9 @@ func _get_or_create_block(block_definition: BlockDefinition) -> Block:
 		block.drag_started.connect(func(block: Block): block_picked.emit(block))
 		_blocks_container.add_child(block)
 		_blocks[block_definition.name] = block
+	else:
+		# If the block is being reused, make sure the context corresponds to
+		# the current BlockCode node.
+		block.refresh_context()
 
 	return block