Can't get SplitLayoutPanel working - GWT + UIBinder are driving me crazy

Question

...
<g:VerticalPanel styleName="{style.mainVerticalPanel}">
    <g:SplitLayoutPanel>
    <g:north size="700">
        <g:VerticalPanel>
                <g:ScrollPanel styleName="{style.conversationPanelContainer}">
                    <g:FlexTable ui:field="conversationPanel" styleName="{style.conversationPanel}"></g:FlexTable>
                </g:ScrollPanel>
                <g:HorizontalPanel styleName="{style.messageTextAndSendPanel}">
                    <g:TextBox ui:field="messageText" styleName="{style.messageText}"></g:TextBox><g:Button ui:field="sendButton">Send</g:Button>
                </g:HorizontalPanel>
        </g:VerticalPanel>
    </g:north>
    <g:south size="300">
    <g:button>TestButton</g:button>
    </g:south>
    </g:SplitLayoutPanel>
</g:VerticalPanel>
...

Anything look wrong with this? All I'm trying to do is make a simple split panel but whenever I run this all I get is a blank page. Without any of the SplitPanel stuff, it works fine. The same happens with DockLayoutPanel.

Answer 1

OK, got it working (see older versions of this answer for previous attempts ;)).

My solution is based on Mail example. The working code:

public class SplitTest implements EntryPoint {

    private static TestUiBinder uiBinder = GWT.create(TestUiBinder.class);

    interface TestUiBinder extends UiBinder<SplitLayoutPanel, SplitTest> {
    }

    /**
     * This is the entry point method.
     */
    public void onModuleLoad() {
        SplitLayoutPanel outer = uiBinder.createAndBindUi(this);

        RootLayoutPanel.get().add(outer);
    }
}

UiBinder *.ui.xml:

<!DOCTYPE ui:UiBinder SYSTEM "http://dl.google.com/gwt/DTD/xhtml.ent">
<ui:UiBinder xmlns:ui="urn:ui:com.google.gwt.uibinder"
  xmlns:g="urn:import:com.google.gwt.user.client.ui">
  <ui:style>
    .conversationPanelContainer, .conversationPanel, .messageTextAndSendPanel, .messageText {
      font-weight: bold;
    }
  </ui:style>
    <g:SplitLayoutPanel>
    <g:north size="700">
        <g:VerticalPanel>
                <g:ScrollPanel styleName="{style.conversationPanelContainer}">
                    <g:FlexTable ui:field="conversationPanel" styleName="{style.conversationPanel}"></g:FlexTable>
                </g:ScrollPanel>
                <g:HorizontalPanel styleName="{style.messageTextAndSendPanel}">
                    <g:TextBox ui:field="messageText" styleName="{style.messageText}"></g:TextBox><g:Button ui:field="sendButton">Send</g:Button>
                </g:HorizontalPanel>
        </g:VerticalPanel>
    </g:north>
    <g:south size="300">
    <g:Button>TestButton</g:Button>
    </g:south>
    </g:SplitLayoutPanel>
</ui:UiBinder> 

Note a number of things:

• First of all: you had an error in your UiBinder XML template: it's <g:Button>, not <g:button> (case sensitive)
• The use of RootLayoutPanel instead of the usual RootPanel
• I'm still a bit confused about the whole LayoutPanels thingy - in the Mail example they use a SplitLayoutPanel nested in a DockLayoutPanel, yet only the DockLayoutPanel is explicitly added to the RootLayoutPanel - am I to understand that the SplitLayoutPanel automagically also gets added (so that it can receive resize events, etc)? How about some other Widgets nested in the main LayoutPanel - do they have to be explicitly added to the RootLayoutPanel or only if they are the root of that Widget/Composite or is that not even possible? I don't really have time atm to pursue this further - I'll leave it as a homework for someone else ;)

BTW: I've checked this code under Quirks mode and Standards mode - I don't see a difference, both work O_o (though, this is a simple use of the SplitLayoutPanel - more complex examples will probably result in some weird behavior in Quirks mode and/or rendering errors)

Answer 2

Which doctype are you using? These panels only work in standards mode (at least with some broswers). If you use quirks mode, then it often happens, that you get a blank page with these panels.

Check your HTML file. It should ideally start with:

<!DOCTYPE html>

Or alternatively some other doctype that results in standards mode (but make sure to type it in 100% verbatim), see http://hsivonen.iki.fi/doctype/