Improve selectbox

core/build.gradle.kts

core/package-lock.json

core/package.json

core/src/scss/5_components/_menu.scss

core/src/scss/5_components/_selectbox.scss

core/src/scss/5_components/_textfield.scss

core/src/ts/components/components.ts

core/src/ts/components/menu.ts

core/src/ts/components/selectbox.ts

core/src/ts/components/selectbox/Select.ts

core/src/ts/components/selectbox/SelectControls.ts

core/src/ts/components/selectbox/SelectGroup.ts

core/src/ts/components/selectbox/SelectItem.ts

core/src/ts/components/selectbox/SelectOption.ts

core/src/ts/components/selectbox/SelectSearch.ts

core/src/ts/components/text.ts

documentation/src/routes/components/menu/+page.svelte

documentation/src/routes/components/selectbox/+page.svelte