How can I make my MC stay in place?

programming flash
1

Hello,

I have an image that is twice the size of my scene and four buttons with actionsscripts to control the scrolling sideways.
On the scene have a movieclip with a dot that changes its x and y coordinates based on input in my webbrowser.
When I scroll the image sideways and up and down I want my movieclip to stay in the same place all the time which it does untill I get to the edge of the image and my movie clip just keeps going :puzzle: this of course makes it so that my movie clip no longer is placed on the x and y positions that I enter.

this is the script i use on my buttons (this being the left button but you get the idea)

_root.imgholder._x -= 3;
if (_root.imgholder._x < -700) {
    setProperty ("_root.imgholder", _x, "-700");
}
_root.mark._x -= 3;
if (_root.mark._x < -700) {
    setProperty ("_root.mark", _x, "-700");
}

So any points on how to get my movie clip to stay in place?

Thanks in advance