优化代码

internal/ui/overlay.go

@@ -64,7 +64,8 @@ func newOverlay(app fyne.App, shot image.Image, vd win32.Rect,
 		objs = append(objs, o.dims[i])
 	}
 	for i := range o.edges {
-		o.edges[i] = canvas.NewRectangle(color.NRGBA{R: 0x5A, G: 0xC8, B: 0xFF, A: 0xFF})
+		// 描边跟着主题走：黑白主题下是纯白/纯黑，不会残留彩色。
+		o.edges[i] = canvas.NewRectangle(lookupColor(theme.ColorNameForeground))
 		objs = append(objs, o.edges[i])
 	}
 	o.hint = canvas.NewText("拖拽框选区域 · Esc 取消", color.White)