travel(-1)} disabled={i === 0}>undo
travel(+1)} disabled={i === undoStack.length - 1}>redo
{#each circles as circle}
select(circle, event)} on:contextmenu|stopPropagation|preventDefault={() => { adjusting = !adjusting; if (adjusting) selected = circle; }} fill={circle === selected ? '#ccc' : 'white'} /> {/each}
{#if adjusting}
adjust diameter of circle at {selected.cx}, {selected.cy}
{/if}