Undo botton to revert source code after edit

composeApp/src/commonMain/kotlin/mg/dot/feufaro/ui/DrawerUI.kt

@@ -106,6 +106,20 @@ fun MainScreenWithDrawer(
     val currentActiveFilePath = sharedScreenModel.activeFilePath.value
     val fileName = currentActiveFilePath.substringAfterLast('/')
 
+    var sourceTitle = sharedScreenModel.songTitle.value
+    val originalPath = remember(sourceTitle) {
+        if (!currentActiveFilePath.contains("_tmp") && !currentActiveFilePath.contains("/tmp/")) {
+            currentActiveFilePath
+        } else {
+            currentActiveFilePath
+        }
+    }
+
+    var sourceContent = sharedScreenModel.fileContent.value ?: ""
+    var codeContent by remember { mutableStateOf(sourceContent?: "") }
+    LaunchedEffect(sourceContent) {
+        codeContent = sourceContent
+    }
     val saveLauncher = rememberFileSaveLauncher { chosenPath ->
         if (chosenPath != null) {
             scope.launch(Dispatchers.IO) {
@@ -246,7 +260,13 @@ fun MainScreenWithDrawer(
                         ) {
                             FloatingActionButton(
                                 onClick = {
-                                    //sharedScreenModel.
+                                    scope.launch {
+                                        codeContent = sourceContent
+
+                                        withContext(Dispatchers.Main) {
+                                            solfaScreenModel.loadExternalFile(originalPath)
+                                        }
+                                    }
                                 }, modifier = Modifier.alpha(0.45f)
                             ) {
                                 Icon(