--- a/svghmi/i18n.py	Wed Mar 31 15:28:09 2021 +0200
+++ b/svghmi/i18n.py	Wed Mar 31 15:30:07 2021 +0200
@@ -68,11 +68,15 @@
     with open(fname, 'w') as POT_file:
         w.write(POT_file)
 
+def GetPoFiles(dirpath):
+    po_files = [fname for fname in os.listdir(dirpath) if fname.endswith(".po")]
+    po_files.sort()
+    return po_files
+
 def ReadTranslations(dirpath):
     """ Read all PO files from a directory and return a list of (langcode, translation_dict) tuples """
 
-    po_files = [fname for fname in os.listdir(dirpath) if fname.endswith(".po")]
-    po_files.sort()
+    po_files = GetPoFiles(dirpath)
 
     translations = []
     for po_fname in po_files:

--- a/svghmi/svghmi.py	Wed Mar 31 15:28:09 2021 +0200
+++ b/svghmi/svghmi.py	Wed Mar 31 15:30:07 2021 +0200
@@ -28,7 +28,8 @@
 from editors.ConfTreeNodeEditor import ConfTreeNodeEditor
 from XSLTransform import XSLTransform
 from svghmi.i18n import EtreeToMessages, SaveCatalog, ReadTranslations,\
-                        MatchTranslations, TranslationToEtree, open_pofile
+                        MatchTranslations, TranslationToEtree, open_pofile,\
+                        GetPoFiles
 from svghmi.hmi_tree import HMI_TYPES, HMITreeNode, SPECIAL_NODES 
 from svghmi.ui import SVGHMI_UI
 from svghmi.fonts import GetFontTypeAndFamilyName, GetCSSFontFaceFromFontFile
@@ -400,13 +401,17 @@
 
         return ret
 
-    def GetFonts(self, _context):
+    def GetFontsFiles(self):
         project_path = self.CTNPath()
         fontdir = os.path.join(project_path, "fonts") 
+        if os.path.isdir(fontdir):
+            return [os.path.join(fontdir,f) for f in sorted(os.listdir(fontdir))]
+        return []
+
+    def GetFonts(self, _context):
         css_parts = []
 
-        for f in sorted(os.listdir(fontdir)):
-            fontfile = os.path.join(fontdir,f)
+        for fontfile in self.GetFontsFiles():
             if os.path.isfile(fontfile):
                 css_parts.append(GetCSSFontFaceFromFontFile(fontfile))
 
@@ -446,13 +451,18 @@
 
             hasher = hashlib.md5()
             hmi_tree_root._hash(hasher)
-            with open(svgfile, 'rb') as afile:
-                while True:
-                    buf = afile.read(65536)
-                    if len(buf) > 0:
-                        hasher.update(buf)
-                    else:
-                        break
+            filestocheck = [svgfile] + \
+                           GetPoFiles(self.CTNPath()) + \
+                           self.GetFontsFiles()
+
+            for filetocheck in filestocheck:
+                with open(filetocheck, 'rb') as afile:
+                    while True:
+                        buf = afile.read(65536)
+                        if len(buf) > 0:
+                            hasher.update(buf)
+                        else:
+                            break
             digest = hasher.hexdigest()
 
             if os.path.exists(hash_path):

--- a/svghmi/ui.py	Wed Mar 31 15:28:09 2021 +0200
+++ b/svghmi/ui.py	Wed Mar 31 15:30:07 2021 +0200
@@ -150,6 +150,7 @@
         sizer.Fit(self)
         self.Bind(wx.EVT_BUTTON, self.OnSelectLibDir, self.libbutton)
         self.preview.Bind(wx.EVT_PAINT, self.OnPaint)
+        self.preview.Bind(wx.EVT_LEFT_DOWN, self.OnLeftDown)
 
         self.Bind(wx.EVT_TREE_SEL_CHANGED, self.OnWidgetSelection, self.widgetpicker)
 
@@ -272,6 +273,16 @@
         self.ValidateWidget()
         self.Refresh()
 
+    def OnLeftDown(self, evt):
+        if self.selected_SVG is not None:
+            # TODO replace with generated widget file
+            filename = self.selected_SVG
+            data = wx.FileDataObject()
+            data.AddFile(filename)
+            dropSource = wx.DropSource(self)
+            dropSource.SetData(data)
+            dropSource.DoDragDrop(wx.Drag_AllowMove)
+
     def ValidateWidget(self):
         if self.selected_SVG is not None:
             if self.hmitree_node is not None: