The Dropper tool in Flash is somewhat different from those found in standard graphics software. In other software, the dropper is employed to pick a color from an image, however, in Flash the dropper tool not only picks up the color but also the properties of a fill or line.
Note that the Dropper has no modifiers. When you click on an outline with the dropper tool, the properties of the line such as color, thickness and style are picked up and Flash then activates the Ink Bottle since it understands that you would now be using this tool.
Similarly, if you click on an objects' fill with the dropper, Flash activates the Paint Bottle with the same properties as those if the object fill.