Use desktopName from package.json for StartupWMClass in Linux desktop entries

packages/app-builder-lib/src/options/metadata.ts

@@ -50,6 +50,8 @@ export interface Metadata {
   readonly productName?: string | null
   /** @private */
   readonly main?: string | null
+  /** @private */
+  readonly desktopName?: string | null
 }
 
 export interface AuthorMetadata {

packages/app-builder-lib/src/targets/LinuxTargetHelper.ts

@@ -129,6 +129,17 @@ export class LinuxTargetHelper {
       }
     }
 
+    // https://github.com/electron-userland/electron-builder/issues/7159
+    // Electron uses desktopName from package.json to set the app_id, which should match StartupWMClass.
+    // https://github.com/electron/electron/blob/9a7b73b5334f1d72c08e2d5e94106706ed751186/lib/browser/init.ts#L128-L133
+    const desktopName = packager.info.metadata.desktopName
+    let wmClass: string
+    if (!isEmptyOrSpaces(desktopName)) {
+      wmClass = desktopName!.replace(/\.desktop$/, "")
+    } else {
+      wmClass = appInfo.productName
+    }
+
     const desktopMeta: any = {
       Name: appInfo.productName,
       Exec: exec,
@@ -140,7 +151,7 @@ export class LinuxTargetHelper {
       // to get WM_CLASS of running window: xprop WM_CLASS
       // StartupWMClass doesn't work for unicode
       // https://github.com/electron/electron/blob/2-0-x/atom/browser/native_window_views.cc#L226
-      StartupWMClass: appInfo.productName,
+      StartupWMClass: wmClass,
       ...extra,
       ...(targetSpecificOptions.desktop?.entry ?? {}),
     }

test/snapshots/linux/linuxPackagerTest.js.snap

@@ -42,6 +42,35 @@ exports[`AppImage - default icon, custom executable and custom desktop 2`] = `
 
 exports[`AppImage - deprecated systemIntegration 1`] = `"ERR_ELECTRON_BUILDER_INVALID_CONFIGURATION"`;
 
+exports[`AppImage - desktopName sets StartupWMClass 1`] = `
+"[Desktop Entry]
+Name=Signal
+Exec=AppRun --no-sandbox %U
+Terminal=false
+Type=Application
+Icon=testapp
+StartupWMClass=signal
+Comment=Test Application (test quite “ #378)
+Categories=Development;
+"
+`;
+
+exports[`AppImage - desktopName sets StartupWMClass 2`] = `
+{
+  "linux": [
+    {
+      "arch": "x64",
+      "file": "Signal-1.1.0.AppImage",
+      "updateInfo": {
+        "blockMapSize": "@blockMapSize",
+        "sha512": "@sha512",
+        "size": "@size",
+      },
+    },
+  ],
+}
+`;
+
 exports[`AppImage 1`] = `
 {
   "linux": [

test/src/linux/linuxPackagerTest.ts

@@ -319,6 +319,34 @@ test.ifNotWindows("no-author-email", ({ expect }) =>
   )
 )
 
+test.ifNotWindows("AppImage - desktopName sets StartupWMClass", ({ expect }) =>
+  app(
+    expect,
+    {
+      targets: appImageTarget,
+      config: {
+        productName: "Signal",
+      },
+      effectiveOptionComputed: async it => {
+        const content: string = it.desktop
+        expect(
+          content
+            .split("\n")
+            .filter(it => !it.includes("X-AppImage-BuildId") && !it.includes("X-AppImage-Version"))
+            .join("\n")
+        ).toMatchSnapshot()
+        return Promise.resolve(false)
+      },
+    },
+    {
+      projectDirCreated: projectDir =>
+        modifyPackageJson(projectDir, data => {
+          data.desktopName = "signal.desktop"
+        }),
+    }
+  )
+)
+
 test.ifNotWindows("forbid desktop.Exec", ({ expect }) =>
   appThrows(expect, {
     targets: appImageTarget,