disable save dialog extension filtering for now as there are issues

src/vs/workbench/browser/parts/editor/untitledEditorInput.ts

@@ -77,7 +77,7 @@ export class UntitledEditorInput extends EditorInput implements IResourceEditorI
 	public suggestFileName(): string {
 		if (!this.hasAssociatedFilePath) {
 			let mime = this.getMime();
-			if (mime) {
+			if (mime && mime !== MIME_TEXT /* do not suggest when the mime type is simple plain text */) {
 				return suggestFilename(mime, this.getName());
 			}
 		}

src/vs/workbench/parts/files/electron-browser/textFileServices.ts

@@ -371,8 +371,12 @@ export class TextFileService extends BrowserTextFileService {
 			defaultPath: defaultPath
 		};
 
-		// Filters are only working well on Windows it seems
-		if (!isWindows) {
+		// Filters are working flaky in Electron and there are bugs. On Windows they are working
+		// somewhat but we see issues:
+		// - https://github.com/atom/electron/issues/3556
+		// - https://github.com/Microsoft/vscode/issues/451
+		// Until these issues are resolved, we disable the dialog file extension filtering.
+		if (true) {
 			return options;
 		}