unload theme fonts on theme change

Vocaluxe/Base/CFont.cs

@@ -123,6 +123,11 @@ namespace Vocaluxe.Base
             fo.Dispose();
         }
 
+        public void UnloadTexture()
+        {
+            CDraw.RemoveTexture(ref Texture);
+        }
+
         private float GetFactor(char chr, TextFormatFlags flags)
         {
             if (CFonts.Style == EStyle.Normal)
@@ -277,6 +282,15 @@ namespace Vocaluxe.Base
             _htGlyphs.Add(chr, _Glyphs.Count - 1);
             CFonts.Height = h;
         }
+
+        public void UnloadAllGlyphs()
+        {
+            foreach (CGlyph glyph in _Glyphs)
+            {
+                glyph.UnloadTexture();
+            }
+            _Glyphs.Clear();
+        }
     }
 
     struct SFont
@@ -854,6 +868,27 @@ namespace Vocaluxe.Base
                 writer.WriteEndElement();
         }
 
+        public static void UnloadThemeFonts(string ThemeName)
+        {
+            if (_Fonts.Count == 0)
+                return;
+
+            int Index = 0;
+            while (Index < _Fonts.Count)
+            {
+                if (_Fonts[Index].IsThemeFont && _Fonts[Index].ThemeName == ThemeName)
+                {
+                    _Fonts[Index].Normal.UnloadAllGlyphs();
+                    _Fonts[Index].Italic.UnloadAllGlyphs();
+                    _Fonts[Index].Bold.UnloadAllGlyphs();
+                    _Fonts[Index].BoldItalic.UnloadAllGlyphs();
+                    _Fonts.RemoveAt(Index);
+                }
+                else
+                    Index++;
+            }
+        }
+
         private static int GetFontIndex(string ThemeName, string FontName)
         {
             if (ThemeName == String.Empty || FontName == String.Empty)

Vocaluxe/Screens/CScreenOptionsTheme.cs

@@ -183,6 +183,7 @@ namespace Vocaluxe.Screens
                 _OldTheme = SelectSlides[htSelectSlides(SelectSlideTheme)].Selection;
 
                 CTheme.UnloadSkins();
+                CFonts.UnloadThemeFonts(CConfig.Theme);
                 CTheme.ListSkins();
                 CConfig.Skin = CTheme.SkinNames[0];
                 _OldSkin = 0;
@@ -205,6 +206,7 @@ namespace Vocaluxe.Screens
                 _OldTheme = SelectSlides[htSelectSlides(SelectSlideTheme)].Selection;
 
                 CTheme.UnloadSkins();
+                CFonts.UnloadThemeFonts(CConfig.Theme);
                 CTheme.ListSkins();
                 CConfig.Skin = CTheme.SkinNames[0];
                 _OldSkin = 0;