diff --git a/DialogToolkit.cpp b/DialogToolkit.cpp
index c7d2c12..4db508b 100644
--- a/DialogToolkit.cpp
+++ b/DialogToolkit.cpp
@@ -222,7 +222,7 @@ bool DialogToolkit::MultipleImagesDialog::closed()
 std::string saveSessionFileDialog(const std::string &label, const std::string &path)
 {
     std::string filename = "";
-    char const * save_pattern[1] = { VIMIX_FILES_PATTERN };
+    char const * save_pattern[1] = { VIMIX_FILE_PATTERN };
 
 #if USE_TINYFILEDIALOG
     char const * save_file_name;
@@ -273,9 +273,8 @@ std::string saveSessionFileDialog(const std::string &label, const std::string &p
     wait_for_event();
 #endif
 
-    std::string extension = filename.substr(filename.find_last_of(".") + 1);
-    if (!filename.empty() && extension != "mix")
-        filename += ".mix";
+    if (!filename.empty() && !SystemToolkit::has_extension(filename, VIMIX_FILE_EXT ) )
+        filename += std::string(".") + VIMIX_FILE_EXT;
 
     return filename;
 }
@@ -285,7 +284,7 @@ std::string openSessionFileDialog(const std::string &label, const std::string &p
 {
     std::string filename = "";
     std::string startpath = SystemToolkit::file_exists(path) ? path : SystemToolkit::home_path();
-    char const * open_pattern[1] = { VIMIX_FILES_PATTERN };
+    char const * open_pattern[1] = { VIMIX_FILE_PATTERN };
 
 #if USE_TINYFILEDIALOG
     char const * open_file_name;
diff --git a/DialogToolkit.h b/DialogToolkit.h
index 8b73054..659c1ba 100644
--- a/DialogToolkit.h
+++ b/DialogToolkit.h
@@ -6,13 +6,6 @@
 #include <vector>
 #include <future>
 
-#define VIMIX_FILES_PATTERN "*.mix"
-#define MEDIA_FILES_PATTERN "*.mix", "*.mp4", "*.mpg", "*.mpeg", "*.m2v", "*.m4v", "*.avi", "*.mov",\
-    "*.mkv", "*.webm", "*.mod", "*.wmv", "*.mxf", "*.ogg",\
-    "*.flv", "*.hevc", "*.asf", "*.jpg", "*.png",  "*.gif",\
-    "*.tif", "*.tiff", "*.webp", "*.bmp", "*.ppm", "*.svg,"
-#define IMAGES_FILES_PATTERN "*.jpg", "*.png", "*.bmp", "*.ppm", "*.gif"
-
 namespace DialogToolkit
 {
 
diff --git a/Mixer.cpp b/Mixer.cpp
index 24c70a8..b1d360d 100644
--- a/Mixer.cpp
+++ b/Mixer.cpp
@@ -244,8 +244,7 @@ Source * Mixer::createSourceFile(const std::string &path)
     if ( SystemToolkit::file_exists( path ) ) {
 
         // test type of file by extension
-        std::string ext = SystemToolkit::extension_filename(path);
-        if ( ext == "mix" )
+        if ( SystemToolkit::has_extension(path, VIMIX_FILE_EXT ) )
         {
             // create a session source
             SessionFileSource *ss = new SessionFileSource;
diff --git a/SystemToolkit.cpp b/SystemToolkit.cpp
index 303704d..d80c67b 100644
--- a/SystemToolkit.cpp
+++ b/SystemToolkit.cpp
@@ -163,6 +163,14 @@ string SystemToolkit::extension_filename(const string& filename)
     return ext;
 }
 
+bool SystemToolkit::has_extension(const std::string& filename, const std::string& extension)
+{
+    std::string ext = extension_filename(filename);
+    std::transform (ext.begin(), ext.end(), ext.begin(), ::tolower);
+
+    return ext.compare(extension) == 0;
+}
+
 std::string SystemToolkit::home_path()
 {
     string homePath;
diff --git a/SystemToolkit.h b/SystemToolkit.h
index b7bb44b..b80acb8 100644
--- a/SystemToolkit.h
+++ b/SystemToolkit.h
@@ -44,6 +44,7 @@ namespace SystemToolkit
 
     // extract the extension of a filename
     std::string extension_filename(const std::string& filename);
+    bool has_extension(const std::string& filename, const std::string& extension);
 
     // tests if dir is a directory and return its path, empty string otherwise
     std::string path_directory(const std::string& path);
diff --git a/UserInterfaceManager.cpp b/UserInterfaceManager.cpp
index a6a328e..eabea6b 100644
--- a/UserInterfaceManager.cpp
+++ b/UserInterfaceManager.cpp
@@ -5166,6 +5166,9 @@ void Navigator::RenderMainPannelVimix()
 
     // fill the session list depending on the mode
     static std::list<std::string> sessions_list;
+    static std::list<std::string>::iterator _file_over = sessions_list.end();
+    static std::list<std::string>::iterator _displayed_over = sessions_list.end();
+
     // change session list if changed
     if (selection_session_mode_changed || Settings::application.recentSessions.changed || Settings::application.recentFolders.changed) {
 
@@ -5179,15 +5182,15 @@ void Navigator::RenderMainPannelVimix()
         // selection MODE 1 : LIST FOLDER
         else if ( selection_session_mode == 1) {
             // show list of vimix files in folder
-            sessions_list = SystemToolkit::list_directory( Settings::application.recentFolders.path, { VIMIX_FILES_PATTERN });
+            sessions_list = SystemToolkit::list_directory( Settings::application.recentFolders.path, { VIMIX_FILE_PATTERN });
         }
         // indicate the list changed (do not change at every frame)
         selection_session_mode_changed = false;
+        _file_over = sessions_list.end();
+        _displayed_over = sessions_list.end();
     }
 
     {
-        static std::list<std::string>::iterator _file_over = sessions_list.end();
-        static std::list<std::string>::iterator _displayed_over = sessions_list.end();
         static bool _tooltip = 0;
 
         // display the sessions list and detect if one was selected (double clic)
diff --git a/defines.h b/defines.h
index 9f4ced4..fec88b4 100644
--- a/defines.h
+++ b/defines.h
@@ -9,6 +9,14 @@
 #define MAX_RECENT_HISTORY 20
 #define MAX_SESSION_LEVEL 3
 
+#define VIMIX_FILE_EXT "mix"
+#define VIMIX_FILE_PATTERN "*.mix"
+#define MEDIA_FILES_PATTERN "*.mix", "*.mp4", "*.mpg", "*.mpeg", "*.m2v", "*.m4v", "*.avi", "*.mov",\
+    "*.mkv", "*.webm", "*.mod", "*.wmv", "*.mxf", "*.ogg",\
+    "*.flv", "*.hevc", "*.asf", "*.jpg", "*.png",  "*.gif",\
+    "*.tif", "*.tiff", "*.webp", "*.bmp", "*.ppm", "*.svg,"
+#define IMAGES_FILES_PATTERN "*.jpg", "*.png", "*.bmp", "*.ppm", "*.gif"
+
 #define MINI(a, b)  (((a) < (b)) ? (a) : (b))
 #define MAXI(a, b)  (((a) > (b)) ? (a) : (b))
 #define ABS(a)	   (((a) < 0) ? -(a) : (a))