Switch single instance on per default.

CHANGELOG.md

@@ -9,9 +9,8 @@
 <a name="breaking_changes_not_yet_released">[Breaking Changes:](#breaking_changes_not_yet_released)</a> 
 
 - [filesystem] Adjusted the "Save As" mechanism. It now assumes that `Saveable.getSnapshot()` returns a full snapshot of the editor model [#13689](https://github.com/eclipse-theia/theia/pull/13689). 
-
--->
-
+- [electron] Switch single instance on per default [#13831](https://github.com/eclipse-theia/theia/pull/13831) - contributed on behalf of STMicroelectronics
+ -->
 ## 1.50.0 - 06/03/2024
 
 - [application-package] bumped the default supported API from `1.88.1` to `1.89.1` [#13738](https://github.com/eclipse-theia/theia/pull/13738) - contributed on behalf of STMicroelectronics

dev-packages/application-package/src/application-props.ts

@@ -183,7 +183,7 @@ export namespace FrontendApplicationConfig {
 export type BackendApplicationConfig = RequiredRecursive<BackendApplicationConfig.Partial>;
 export namespace BackendApplicationConfig {
     export const DEFAULT: BackendApplicationConfig = {
-        singleInstance: false,
+        singleInstance: true,
         frontendConnectionTimeout: 0
     };
     export interface Partial extends ApplicationConfig {

packages/core/src/electron-main/electron-main-application.ts

@@ -721,14 +721,19 @@ export class ElectronMainApplication {
     }
 
     protected async onSecondInstance(event: ElectronEvent, argv: string[], cwd: string): Promise<void> {
-        const electronWindows = BrowserWindow.getAllWindows();
-        if (electronWindows.length > 0) {
-            const electronWindow = electronWindows[0];
-            if (electronWindow.isMinimized()) {
-                electronWindow.restore();
-            }
-            electronWindow.focus();
-        }
+        createYargs(this.processArgv.getProcessArgvWithoutBin(argv), process.cwd())
+            .help(false)
+            .command('$0 [file]', false,
+                cmd => cmd
+                    .positional('file', { type: 'string' }),
+                async args => {
+                    this.handleMainCommand({
+                        file: args.file,
+                        cwd: process.cwd(),
+                        secondInstance: true
+                    });
+                },
+            ).parse();
     }
 
     protected onWindowAllClosed(event: ElectronEvent): void {