Uncrasher

<apex:page Controller="AccountMergerController" tabStyle="Account"> 
    
    <apex:form >    
        <apex:pageBlock id="pageBlock1" title="Account Merger"  >         
            <apex:pageMessage summary="Account Merger copies the selected source account's contacts, assigns the new contacts to the Destination Account and prefix's 'merged_' to the source contacts last name and email fields." 
                              severity="info" strength="2" />
    
            <apex:pageBlockButtons location="top" >                
                <apex:commandButton value="Get Source Contacts" action="{!getSourceContacts}" rerender="pageBlock2"/>                     
            </apex:pageBlockButtons>

Uncrasher

<apex:page Controller="AccountMergerController" tabStyle="Account"> 
    
    <apex:form >    
        <apex:pageBlock id="pageBlock1" title="Account Merger"  >         
            <apex:pageMessage summary="Account Merger copies the selected source account's contacts, assigns the new contacts to the Destination Account and prefix's 'merged_' to the source contacts last name and email fields." 
                              severity="info" strength="2" />
    
            <apex:pageBlockButtons location="top" >                
                <apex:commandButton value="Get Source Contacts" action="{!getSourceContacts}" rerender="pageBlock2" />                     
            </apex:pageBlockButtons>