Per-program Flet client app IDs so the dock shows the right icons

Main.py

@@ -1,6 +1,7 @@
 """SaraSuite entry point: installs, updates and removes Sara programs.
 With arguments it runs the command-line mode instead (see Cli.py)."""
 
+import importlib.util
 import os
 import shutil
 import sys
@@ -11,7 +12,7 @@ import flet as ft
 
 from Core import (
     AppName, ApplyAppearance, AssetsDir, BuildTheme, BundledFontFamily, ChipButtonStyle, DataDir,
-    DataHome, EffectiveSettings, LoadConfig, Palette,
+    DataHome, EffectiveSettings, LoadConfig, ManifestsDir, Palette,
 )
 from Dialogs import ShowInstallDialog, ShowOptionsDialog, ShowRemoveDialog, ShowUpdateDialog
 from Installer import Apply, Fetch, FetchCommit, GetStatus, PlanConfigs, PlanRemoval, Remove, SourceVersion
@@ -27,6 +28,15 @@ _MenuEntry = DataHome / "applications" / "SaraSuite.desktop"
 _MenuIcon = DataDir / "SaraSuite.png"
 
 
+def _LoadFletIdentity():
+    # Lives in Programs/ (bundled as data) because installed programs get a
+    # copy of the same file next to them.
+    Spec = importlib.util.spec_from_file_location("FletIdentity", ManifestsDir / "FletIdentity.py")
+    Module = importlib.util.module_from_spec(Spec)
+    Spec.loader.exec_module(Module)
+    return Module
+
+
 def _SetMenuEntry(Enabled: bool) -> None:
     if not Enabled:
         _MenuEntry.unlink(missing_ok=True)
@@ -39,7 +49,7 @@ def _SetMenuEntry(Enabled: bool) -> None:
         "[Desktop Entry]\nType=Application\nName=SaraSuite\n"
         "Comment=Install, update and remove Sara programs\n"
         f"Exec={_AppImage}\nIcon={_MenuIcon}\nTerminal=false\n"
-        f"Categories=System;\nStartupNotify=true\nStartupWMClass={AppName}\n"
+        f"Categories=System;\nStartupNotify=true\nStartupWMClass=srhtnin.{AppName}\n"
     )
 
 
@@ -234,7 +244,8 @@ if __name__ == "__main__":
         from Cli import Run
 
         sys.exit(Run(sys.argv[1:]))
-    # The window's app ID, so the desktop matches it to SaraSuite.desktop
-    # (icon, name) instead of showing it as Flet's generic "com.appveyor.flet".
-    os.environ.setdefault("FLET_APP_ID", AppName)
+    # A Flet client copy with the window app ID srhtnin.SaraSuite, so the
+    # desktop matches the window to SaraSuite.desktop (StartupWMClass) instead
+    # of showing it as "com.appveyor.flet". See Programs/FletIdentity.py.
+    os.environ.setdefault("FLET_VIEW_PATH", _LoadFletIdentity().ClientFor(f"srhtnin.{AppName}"))
     ft.run(Main, assets_dir=str(AssetsDir))