on.text_input = function(t)
	if Cursor_node and Cursor_node.editor.cursor_x then
		local old_top = {line=Cursor_node.editor.screen_top1.line, pos=Cursor_node.editor.screen_top1.pos}
		edit.text_input(Cursor_node.editor, t)
		if not eq(Cursor_node.editor.screen_top1, old_top) then
			Viewport.y = Cursor_node.y + y_of_schema1(Cursor_node.editor, Cursor_node.editor.screen_top1)
			-- Most of the time, we update the screen_top of nodes from Viewport.y.
			-- But here we went the other way.
			-- It's very important to avoid creating a recurrence, to avoid running
			-- both sides of this feedback loop in a single frame. These apps are
			-- not very numerically precise (e.g. we force text lines to start at
			-- integer pixels regardless of zoom, because that keeps text crisp),
			-- and the computations of Viewport.y and node.top will almost certainly
			-- not converge. The resulting bugs are extremely difficult to chase
			-- down.
			-- The optional skip_updating_screen_top_for arg ensures we don't run
			-- the other side of the feedback loop.
			A(--[[skip updating screen_top for]] Cursor_node)
			return
		end
		A()
	end
end