Fix syncing materials via API, show nice message

plugins/UM3NetworkPrinting/src/Messages/MaterialSyncMessage.py

@@ -0,0 +1,39 @@
+# Copyright (c) 2019 Ultimaker B.V.
+# Cura is released under the terms of the LGPLv3 or higher.
+from typing import TYPE_CHECKING
+
+from UM import i18nCatalog
+from UM.Message import Message
+
+
+if TYPE_CHECKING:
+    from ..UltimakerNetworkedPrinterOutputDevice import UltimakerNetworkedPrinterOutputDevice
+
+
+I18N_CATALOG = i18nCatalog("cura")
+
+
+## Message shown when sending material files to cluster host.
+class MaterialSyncMessage(Message):
+
+    # Singleton used to prevent duplicate messages of this type at the same time.
+    __is_visible = False
+
+    def __init__(self, device: "UltimakerNetworkedPrinterOutputDevice") -> None:
+        super().__init__(
+            text = I18N_CATALOG.i18nc("@info:status", "Cura has detected material profiles that were not yet installed "
+                                                      "on the host printer of group {0}.", device.name),
+            title = I18N_CATALOG.i18nc("@info:title", "Sending materials to printer"),
+            lifetime = 10,
+            dismissable = True
+        )
+
+    def show(self) -> None:
+        if MaterialSyncMessage.__is_visible:
+            return
+        super().show()
+        MaterialSyncMessage.__is_visible = True
+
+    def hide(self, send_signal = True) -> None:
+        super().hide(send_signal)
+        MaterialSyncMessage.__is_visible = False