Extend the Hello World example to support incrementing a number by clicking on a button.

In the last section, you built a simple app that says, “Hello, World!” In this section, you will add to that app by creating a button that increments a label. To do that, you need to add the following code after the “Hello, World!” label:

	// Add a new label to the main frame with the text "0"
	// This label will track the number of times the button has been clicked
	numLabel := gi.AddNewLabel(mfr, "numLabel", "0")
	// Make the label redrawable so that it can be updated when the
	// number of times the button has been clicked changes
	numLabel.Redrawable = true
	// Add a new button to the main frame
	button := gi.AddNewButton(mfr, "button")
	// Set the text of the button to "Increment"
	button.Text = "Increment"
	// Keep track of the number of times that the button has been clicked
	numClicked := 0
	// The OnClicked function is called every time the button is clicked
	button.OnClicked(func() {
		// In it, we increment the number of times the button has been clicked
		// Then, we set the text of the number label to the number of the times
		// the button has been clicked. strconv.Itoa converts integers to strings.

Then, run go build and ./myapp if you are on MacOS or Linux and ./myapp.exe if you are on Windows. This should create a window similar to the last one, except with a new label and button. Each time you click the Increment button, the number in the new label should increase by 1. If you click the button 7 times, the app should look like this:

Screenshot of Increment App

Last modified January 22, 2024: removed old deps from go mod (0b4edcc)