1. A method for restoring an occluded window in application sharing, comprising: detecting that an unshared window occludes at least part of a shared window; based on said detecting, (a) creating a first alpha blended image using a first value for the alpha factor; and (b) creating a second alpha blended image using a second value for the alpha factor; and restoring the occluded shared window based on the first and second alpha blended images by: multiplying first pixel values of first pixels in the first alpha blended image by the second alpha factor to generate a first product, multiplying second pixel values of second pixels in the second alpha blended image corresponding to the first pixels by the first alpha factor to generate a second product, and subtracting the second product from the first product to generate a first difference.