Previous versions of ImageGlue attempted to autosize a Canvas which had yet to be initialized. This was required by the text based API, it was hard to know for example how big an image was before drawing it.
In ImageGlue7 we have introduced a new API that allows retrieving information about drawable objects before drawing them. For example you can use XImage to know how big an image is, before drawing it.
We therefore encourage you not to rely on autosizing anymore but to set the Width and Height of the Canvas manually. Basic autosizing is still available, for example when adding an image to a Canvas that has not been initialized, the Canvas will still be initialized to the image size. However for more complex drawing operations you should set the size of the Canvas first.