Checkbox

ui.Checkbox creates a check box toggling a *bool, with a label: a click on the box or its label checks it or unchecks it, as does Space while it has the keyboard focus, and Changed reports a click.

ui.Checkbox(c, &app.settings.Sync, "Sync across devices")
if ui.Checkbox(c, &app.showHidden, "Show hidden files").Changed() {
	app.reload()
}

The check box changes the value itself, the moment the user clicks: read it, or ask Changed for work that follows.

Groups

ui.CheckboxGroup creates a check box over the check boxes built inside it, indented below it, as a list of permissions: it is checked when they all are, mixed when some are, and a click, or Space while it has the focus, checks them all, or none when they all are. Changed reports a click.

ui.CheckboxGroup(c, "Notifications", func() {
	ui.Checkbox(c, &app.mail, "Mail")
	ui.Checkbox(c, &app.calendar, "Calendar")
	ui.Checkbox(c, &app.messages, "Messages")
})

Mixed

ui.CheckboxState is a check box that can be mixed, as a "select all" box in a table's header: checked when every row is, mixed when some are. It sets a *ui.CheckState, ui.CheckOff, ui.CheckOn or ui.CheckMixed, and shows a dash while mixed; a click, or Space while it has the focus, checks it, or unchecks it once it is checked, and Changed reports a click:

all := ui.CheckOff
switch n := app.selected(); {
case n == len(app.rows):
	all = ui.CheckOn
case n > 0:
	all = ui.CheckMixed
}
if ui.CheckboxState(c, &all, "").Label("Select all").Changed() {
	app.selectAll(all == ui.CheckOn)
}

CheckboxGroup is such a check box over the check boxes it holds.

Without a look

ui.CheckboxBase is a check box without a look: a row that toggles its *bool when clicked, which you draw from the value, and ui.CheckboxStateBase one that sets a *ui.CheckState, as CheckboxState does: see custom widgets.

Accessibility

Assistive technology sees a check box named by its label, checked or not, which it toggles as a click does, and one that can be mixed checked, unchecked or mixed. A check box group is a check box, mixed while some are checked, and a group of the others named by its label.