fix: controls couldn't cycle some mpv properties

closes #777

src/uosc/elements/CycleButton.lua

@@ -52,7 +52,7 @@ function CycleButton:init(id, props)
 		self['on_prop_' .. self.prop] = function(self, value) handle_change(self.prop, value) end
 		handle_change(self.prop, state[self.prop])
 	else
-		self:observe_mp_property(self.prop, handle_change)
+		self:observe_mp_property(self.prop, 'string', handle_change)
 	end
 end
 

src/uosc/elements/Element.lua

@@ -182,9 +182,12 @@ end
 
 -- Automatically registers disposer for the observer.
 ---@param name string
----@param callback fun(name: string, value: any)
-function Element:observe_mp_property(name, callback)
-	mp.observe_property(name, 'native', callback)
+---@param type_or_callback string|fun(name: string, value: any)
+---@param callback_maybe nil|fun(name: string, value: any)
+function Element:observe_mp_property(name, type_or_callback, callback_maybe)
+	local callback = type(type_or_callback) == 'function' and type_or_callback or callback_maybe
+	local prop_type = type(type_or_callback) == 'string' and type_or_callback or 'native'
+	mp.observe_property(name, prop_type, callback)
 	self:register_disposer(function() mp.unobserve_property(callback) end)
 end