--- a/svghmi/svghmi.py	Wed Mar 10 09:59:18 2021 +0100
+++ b/svghmi/svghmi.py	Wed Mar 10 10:01:05 2021 +0100
@@ -17,7 +17,6 @@
 import time
 
 import wx
-import wx.dataview as dv
 
 from lxml import etree
 from lxml.etree import XSLTApplyError
@@ -130,6 +129,24 @@
 
         return res
 
+    @classmethod
+    def from_etree(cls, enode):
+        """
+        alternative constructor, restoring HMI Tree from XML backup
+        note: all C-related information is gone, 
+              this restore is only for tree display and widget picking
+        """
+        nodetype = enode.tag
+        attributes = enode.attrib
+        name = attributes["name"]
+        path = attributes["path"].split('.') if "path" in attributes else None 
+        hmiclass = attributes.get("class", None)
+        # hash is computed on demand
+        node = cls(path, name, nodetype, hmiclass=hmiclass)
+        for child in enode.iterchildren():
+            node.children.append(cls.from_etree(child))
+        return node
+
     def traverse(self):
         yield self
         if hasattr(self, "children"):
@@ -343,6 +360,12 @@
         runtimefile.write(svghmiservercode)
         runtimefile.close()
 
+        # Backup HMI Tree in XML form so that it can be loaded without building
+        hmitree_backup_path = os.path.join(buildpath, "hmitree.xml")
+        hmitree_backup_file = open(hmitree_backup_path, 'w')
+        hmitree_backup_file.write(etree.tostring(hmi_tree_root.etree()))
+        hmitree_backup_file.close()
+
         return ((["svghmi"], [(gen_svghmi_c_path, IECCFLAGS)], True), "",
                 ("runtime_00_svghmi.py", open(runtimefile_path, "rb")))
                 #         ^
@@ -353,14 +376,11 @@
 class HMITreeSelector(wx.TreeCtrl):
     def __init__(self, parent):
         global on_hmitree_update
-        wx.TreeCtrl.__init__(self,parent,style=wx.TR_MULTIPLE)# | wx.TR_HIDE_ROOT)
-
-        isz = (16,16)
-        self.il = il = wx.ImageList(*isz)
-        self.fldridx     = il.AddIcon(wx.ArtProvider.GetIcon(wx.ART_FOLDER,      wx.ART_OTHER, isz))
-        self.fldropenidx = il.AddIcon(wx.ArtProvider.GetIcon(wx.ART_FOLDER_OPEN, wx.ART_OTHER, isz))
-        self.fileidx     = il.AddIcon(wx.ArtProvider.GetIcon(wx.ART_NORMAL_FILE, wx.ART_OTHER, isz))
-        self.SetImageList(il)
+        wx.TreeCtrl.__init__(self, parent, style=(
+            wx.TR_MULTIPLE |
+            wx.TR_HAS_BUTTONS |
+            wx.SUNKEN_BORDER |
+            wx.TR_LINES_AT_ROOT))
 
         on_hmitree_update = self.SVGHMIEditorUpdater()
         self.MakeTree()
@@ -372,16 +392,12 @@
                                if c.hmiclass is not None else c.name
                 tc_child = self.AppendItem(current_tc_root, display_name)
                 self.SetPyData(tc_child, None)
-                self.SetItemImage(tc_child, self.fldridx, wx.TreeItemIcon_Normal)
-                self.SetItemImage(tc_child, self.fldropenidx, wx.TreeItemIcon_Expanded)
 
                 self._recurseTree(c,tc_child)
             else:
                 display_name = '{} {}'.format(c.nodetype[4:], c.name)
                 tc_child = self.AppendItem(current_tc_root, display_name)
                 self.SetPyData(tc_child, None)
-                self.SetItemImage(tc_child, self.fileidx, wx.TreeItemIcon_Normal)
-                self.SetItemImage(tc_child, self.fileidx, wx.TreeItemIcon_Expanded)
 
     def MakeTree(self):
         global hmi_tree_root
@@ -394,11 +410,10 @@
         root_display_name = _("Please build to see HMI Tree") if hmi_tree_root is None else "HMI"
         self.root = self.AddRoot(root_display_name)
         self.SetPyData(self.root, None)
-        self.SetItemImage(self.root, self.fldridx, wx.TreeItemIcon_Normal)
-        self.SetItemImage(self.root, self.fldropenidx, wx.TreeItemIcon_Expanded)
 
         if hmi_tree_root is not None:
             self._recurseTree(hmi_tree_root, self.root)
+            self.Expand(self.root)
 
         self.Thaw()
 
@@ -428,6 +443,15 @@
 
     def CreateHMITreeView(self, parent):
         #self.HMITreeView = HMITreeView(self)
+        global hmi_tree_root
+
+        if hmi_tree_root is None:
+            buildpath = self.Controler.GetCTRoot()._getBuildPath()
+            hmitree_backup_path = os.path.join(buildpath, "hmitree.xml")
+            if os.path.exists(hmitree_backup_path):
+                hmitree_backup_file = open(hmitree_backup_path, 'r')
+                hmi_tree_root = HMITreeNode.from_etree(etree.parse(hmitree_backup_file).getroot())
+
         return HMITreeSelector(parent)
 
 class SVGHMI(object):