# onResize `onResize(self)`
This is a custom event which gets triggered as soon as the parent frame gets resized. Here is a example on how to add a onResize event to your button: ```lua local basalt = require("basalt") local main = basalt.createFrame() local aButton = main:addButton():setPosition(3,3) local function onButtonResize(self) local width = main:getWidth() self:setSize(width, 3) end aButton:onResize(onButtonResize) ```