can i make a panel act like a contentplaceholder in a master page ?

 More specifically, what functionality do you want?

Well, you could always put the contentplaceholder inside a panel, if that's what you want.

yes i know that but i wont to make the panel to be a contentplaceholder becouse the contentplaceholdedr is so hard to work with

 Hard to work with? The ContentPlaceHolder can't do anything, except provide a place for a Content element. Putting a ContentPlaceHolder inside a Panel is basically the same thing as giving the contentplaceholder all the properties of a Panel.

yesyesyes i know that is a ok sulotion but the contentplaceholder is one size so if i stretch the panel bigger then the placeholder it wil not work.....

The ContentPlaceHolder doesn't have any size at all. It's just a......placeholder. The fact that it may look a bit strange in the VS master page editor has no impact on the result.