Try the following code to see if that's what you want.
Basically, the WindowOrView class extends window to add a boolean attribute called 'iswindow' - True: it's a window (default); False: the window dressing disappear. Use the checkbox in the window to switch between these 2 states.
<canvas>
<class name="WindowOrView" extends="window">
<!-- set this to False if you want the window resources to disappear -->
<attribute name="iswindow" type="boolean" value="true" setter="setIsWindow( iswindow )"/>
<event name="oniswindow"/>
<!-- the setter for iswindow -->
<method name="setIsWindow" args="value">
this.iswindow = value;
if ( this._initcomplete )
this.showOrHideWindowResources();
if ( this['oniswindow'] )
this.oniswindow.sendEvent( this.iswindow );
</method>
<!-- Show or hide the window skin/border resources, title area, resize
controls, etc., based on the value of iswindow.
(see lz/windowpanel.lzx) -->
<method name="showOrHideWindowResources"> <![CDATA[
// comment/uncomment these lines to see the effect
// 'top', 'middle', and 'bottom' are window skin
// they are resizeview_x objects (see base/resizeview.lzx)
this.top.setVisible( this.iswindow );
this.middle.setVisible( this.iswindow );
this.bottom.setVisible( this.iswindow );
// the left and right grippers in the title_area
//this.title_area.gripper_left.setVisible( this.iswindow );
//this.title_area.gripper_right.setVisible( this.iswindow );
// or just turn the whole title_area on/off if you like
this.title_area.setVisible( this.iswindow );
// because title_area may contain other subviews like icon, title, and
// controls (including the close button)
// the following subviews are defined in window class (lz/window.lzx)
// wframe is the surrounding 1-px border with bgcolor 0x6A6A6A
// we'll make it disappear by setting its bgcolor to null
this.wframe.setBGColor( this.iswindow? 0x6A6A6A : null );
// cannot set its visible to false cause it will make content disappear
// (wcontent is inside wframe; wcontent is the defaultplacement of window)
// the resize control (created only if resizable is True)
//if ( this.resizable )
// this._resizeControl.setVisible( this.iswindow );
// or just set resizable to true/false
this.setAttribute( 'resizable', this.resizable && this.iswindow );
]]> </method>
</class>
<WindowOrView iswindow="${cb.value}" width="150" height="100">
<checkbox name="cb" value="true">iswindow</checkbox>
</WindowOrView>
</canvas>
Modify the code to do other things you like. You may need to study the windowpanel code in the library (lz/windowpanel.lzx). windowpanel is the one that provides the window borders/background etc.; window extends windowpanel to add other things like menubar, toolbar, and the resize control.
style.bordersize is actually not used by windowpanel; only basecolor, textcolor, and bgcolor are used (see _applystyle() method in windowpanel).
Hope this helps.