Extend a Panel In Only One Direction

// Create a panel with a button that will extend the panel size in only one direction (downward in this case).
// The extension is also set at a pre-defined size.
// Features inside the initially hidden extension range can be shown or hidden again using the XtendD button.

Static Constant normaldepth = 80
Static Constant xtendeddepth = 170

Function SamplePanel()

	NewPanel/W=(10,25,255,25+normaldepth)/N=XtendablePanel/K=1 as "Xtend Me"
	ModifyPanel noEdit=1, fixedsize=1
        Button XtendD,pos={4,55},size={15,20},proc=XtendDown,title=">", userData="closed"
	SetDrawLayer UserBack
	DrawLine 22,65,242,65
	CheckBox acheckbox,pos={24,85},size={48,14},title="A Box"
	return 0
end

Function XtendDown(ba) : ButtonControl
	STRUCT WMButtonAction &ba
	
	switch( ba.eventCode )
		case 2: // mouse up
			GetWindow kwTopWin wsize
			strswitch(ba.userData)
				case "closed":
					Button XtendD title="v", userData="opened"
					MoveWindow V_left,V_top,V_right,V_top+(xtendeddepth*72/ScreenResolution)
					break
				case "opened":
					Button XtendD title=">", userData="closed"
					MoveWindow V_left,V_top,V_right,V_top+(normaldepth*72/ScreenResolution)
					break
			endswitch
			break
	endswitch
	return 0
end