feat: scrollable multi-select

[meowgorithm]

This adds a Height(int) setter to MultiSelect prompts.

multiSelect := huh.NewMultiSelect[int]().
	Options(ops...).
	Height(10)

• When Height <= 0 the multi-select auto-sizes itself to the number of fields (as it does currently)
• When Height > 0 the multi-select will behave like a viewport and the visible options will scroll with the cursor

Note that the height here refers to the total height of the multi-select itself including the height of title and the description (if set) however the number of options visible will never be less than 1.

Here’s an example of it in use:

multiselect.mov

And here's what that code looks like:

package main

import (
	"fmt"
	"os"

	"github.com/charmbracelet/huh"
)

func main() {
	const height = 10

	opts := make([]huh.Option[int], 50)
	for i := 0; i < len(opts); i++ {
		opts[i] = huh.Option[int]{
			Key:   fmt.Sprintf("Option %d", i+1),
			Value: i,
		}
	}

	prompt := huh.NewMultiSelect[int]().
		Title("Choose something, will ya?").
		Description(fmt.Sprintf("This prompt is %d cells high and has %d choices", height, len(opts))).
		Options(opts...).
		Height(height)

	if err := prompt.Run(); err != nil {
		fmt.Println("Uh oh: ", err)
		os.Exit(1)
	}
}

Closes #67.

[tetienne]

Thx for implementing this. Do you think it will take a lot of effort to port to Select too?

[chilicat]

Looks great! The list would need some kind of indicator that more items are available. Would it make sense to show this "paging dots"?

[meowgorithm]

@tetienne: Thx for implementing this. Do you think it will take a lot of effort to port to Select too?

Easy enough, see #76.

@chilicat: Looks great! The list would need some kind of indicator that more items are available. Would it make sense to show this "paging dots"?

Agreed, though that will require some updates to themes as well, so we should examine that one in a separate pass.