Inline Edit Support:

Inline Edit Support:
This component provides inline editing support to  <apex:outputField> and  various container components. In order to support inline editing, this component must also be within an <apex:form> tag.

<apex:page standardController="Contact">
    <apex:form >
        <apex:pageBlock mode="inlineEdit">
            <apex:pageBlockButtons >
                <apex:commandButton action="{!edit}" id="editButton" value="Edit"/>
                <apex:commandButton action="{!save}" id="saveButton" value="Save"/>
                <apex:commandButton onclick="resetInlineEdit()" id="cancelButton" value="Cancel"/>
            </apex:pageBlockButtons>
            <apex:pageBlockSection >
                <apex:outputField value="{!contact.lastname}">
                    <apex:inlineEditSupport showOnEdit="saveButton, cancelButton" 
                        hideOnEdit="editButton" event="ondblclick" 
                        changedStyleClass="myBoldClass" resetFunction="resetInlineEdit"/>
                </apex:outputField>
                <apex:outputField value="{!contact.accountId}"/>
                <apex:outputField value="{!contact.phone}"/>
            </apex:pageBlockSection>
        </apex:pageBlock>
    </apex:form>
</apex:page>