The first step in defining a floating view is to create the content nodes that define wht the view looks like. These nodes need to overlay venkman.xul and venkman-floater.xul, because XUL does not support moving nodes between documents.
Content nodes for the ``Breakpoint View'', from venkman-views.xml...
<!-- breakpoint view -->
<floatingview id="breaks" title="&Break.label;" flex="1">
<vbox id="break-view-content" flex="1">
<tree flex="1" id="break-tree" persist="height" hidecolumnpicker="true"
ondblclick="console.views.breaks.onDblClick(event);"
context="context:breaks">
<treecols>
<treecol id="breaks:col-0" label="&BreakCol0.label;"
primary="true" flex="5" persist="hidden width"/>
<splitter class="tree-splitter"/>
<treecol id="breaks:col-1" flex="1" label="&BreakCol1.label;"
persist="hidden width"/>
<splitter class="tree-splitter"/>
</treecols>
<treechildren id="break-body"/>
</tree>
</vbox>
</floatingview>