Hello, 
using uDIG RC 5 I got a heap space   error after adding several layers. Each layer was created from a very small   graphic (png or gif file of less than 1 KB) together with a world file. The   same was true when each layer was created from a small   shapefile.
The intension is as follows: The user   creates a list of locations and these locations are shown on a map. When   creating a new list of locations, the old locations are removed from the map   and the new ones are displayed.
I did it similar to the descriptions   in the FAQ "How do I create a map programmatically" and "I want to add an   image to the map, how do I do that?"
      - I created a map using     createCreateMapCommand     
- I added about ten layers (see     above what the layers looked like) with either createAddManyLayersCommand     (all layers together) or createAddLayerCommand (one layer at a     time)     
- When a new list was created I     removed the old layers using createDeleteLayer command, set the new bounding     box with createSetViewportBBoxCommand and added the new layers to the     map. 
 
After doing these several times I run   into the heap space error. 
I also get this error when I only add and remove one layer (i.e.   location lists with only one entry), but it takes longer to get the   error.
I also tried it "the old way" with   MapFactory.processURLs - with a similar result: The error appeared as well,   but it took longer to get it.
Am I doing it the wrong way? Is there   a better way? 
I also wanted to try RC 6a. Are   there any changes related to the layers view and showing the map? In RC 5   after adding the layer to the map they were displayed at once. In RC 6a I can   see them in the catalog and in the project window, but they do not appear in   the layers view automatically and are not displayed. I'll have a closer look   to that to see whether I get the heap space error in RC 6a as   well.
Michael 
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  User-friendly Desktop Internet GIS (uDig)