I'm trying to use a Map to select object fields.  I want to be able to select certain fields and then make queries on those fields.
I use describe to get the fields from selected objects and then put them into a map.  I want to be able to select certain fields and populate them into a correspong map.  

I am trying to use the component found here http://blogs.developerforce.com/developer-relations/2012/06/a-multiselect-picklist-visualforce-component.html but it's not working for my map.  I've tried using a normal selectList and I can display the fields (though it's ugly atm) but after selecting it doesn't populate to the correspoding map.  I've tried using a List as well and got the same results.

My visualforce page here.

<apex:page standardController="Custom_Object__c" extensions="customController">
    <apex:pageBlock >
        <apex:form >
            <apex:commandButton value="Select Objects" action="{!getObjectFields}" rerender="picklists"/>
            <apex:commandbutton value="Get Selected Fields" action="{!printOptions}" rerender="out"/>
           
        <apex:pageBlockSection > 
           
            <c:MultiselectPicklist leftLabel="Objects" leftOptions="{!SupportedObjects}" rightLabel="Objects" rightoptions="{!SelectedObjects}" size="14" width="150px"/>  <!--This works-->
           
        </apex:pageBlockSection>
        </apex:form>
    </apex:pageBlock>

    <apex:pageBlock >
        <apex:form >
        <apex:pageBlockSection  >
            <apex:outputPanel id="picklists">
           
            <apex:repeat value="{!objectFieldMap}" var="key">
                <apex:selectList value="{!selectedFieldsMap[key]}" multiselect="true"><--I can see the fields, but can't populate-->
                    <apex:selectOptions value="{!objectFieldMap[key]}"></apex:selectOptions>
                </apex:selectList>
                <!--<c:MultiselectPicklist leftLabel="Objects" leftOptions="{!objectFieldMap[key]}" rightLabel="Objects" rightoptions="{!selectedFieldsMap[key]}" size="14" width="150px"/> This doesn't work -->
            </apex:repeat>           
            </apex:outputPanel>
           
        </apex:pageBlockSection>
     </apex:form>
    </apex:pageBlock>
</apex:page>

My Controller here

public class customController{
   
    public List<selectOption> supportedObjects {get; set;}//Used for component to get objects -- this works
    public List<selectOption> SelectedObjects {get; set;}//Used for component to get objects -- this works
   
    public Map<String,SelectOption[]> objectFieldMap{get;set;}//<-- This contains all fields for an object
    public Map<String,String[]> selectedFieldsMap{get;set;}//<-- This should receive the selected fields
   
    public List<List<SelectOption>> fieldSelections{get;set;}//<-- This contains all fields for an object when I tried using a list
    public List<List<String>> selectedFields{get;set;}//<--This should receive the selected fields when I tried using a list
   
    Map<String, Schema.SObjectType> gd = Schema.getGlobalDescribe(); 
   
    public LookbookCreationController(ApexPages.StandardController stdController){
        SelectedObjects = new List<SelectOption>();
        fieldSelections= new List<List<SelectOption>>();
        init();
    }
   
    private void init(){
   
        supportedObjects = new List<selectoption>();
        Schema.DescribeFieldResult fieldResult = Custom_Object__c.Object__c.getDescribe();//Mulitselect picklist on custom object that has a list of objects to use
        for( Schema.PicklistEntry e : fieldResult.getPicklistValues() ){
            supportedObjects.add( new SelectOption( e.getLabel(), e.getValue() ) );  
        }
    }
   
    public PageReference printOptions(){
        System.debug( selectedFieldsMap );//Using this to see if the map is populated.  
        return null;
    }
   
   
    public void getObjectFields(){
       
        selectedFields = new List<List<String>>();
        objectFieldMap = new Map<String,List<SelectOption>>();
        selectedFieldsMap = new Map<String,List<String>>();

        for(SelectOption o : SelectedObjects){
           
           //Describe stuff to get all fields for the selected Objects. This part works
            List<SelectOption> options = new List<SelectOption>();
            Schema.SObjectType systemObjectType = gd.get(o.getValue());
            Schema.DescribeSObjectResult r = systemObjectType.getDescribe();
            Map<String, Schema.SObjectField> M = r.fields.getMap();
            for( Schema.SObjectField fieldAPI : M.values() ) {
                options.add(new SelectOption(fieldAPI.getDescribe().getName() , fieldAPI.getDescribe().getLabel())) ; 
            } 
            objectFieldMap.put( o.getValue(), options );
            selectedFieldsMap.put( o.getValue(), new List<String>() );
            fieldSelections.add( options );
            selectedFields.add( new List<String>() );
        }
    }


When I use the Map or List, things display but selecting doesn't populate.  Using the component I get the following error Cannot convert the value of '{!leftOptions}' to the expected type. After selecting the objects and trying to display the component.