mobile/DCdownload: try harder to get the right elements selected

The number of possible sequences of events when the user is connecting a
USB device is rather surprising. These changes try to ensure that in
every case we get USB connection information we do in fact show the
correct (or best guess) connection.

See #2686

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

mobile-widgets/qml/DownloadFromDiveComputer.qml

@@ -157,6 +157,16 @@ Kirigami.Page {
 					verticalAlignment: Text.AlignVCenter
 					elide: Text.ElideRight
 				}
+				onCountChanged: {
+					// ensure that pick the first entry once we have any
+					// entries in the connection list
+					if (count === 0)
+						currentIndex = -1
+					else if (currentIndex === -1)
+						currentIndex = 0
+
+				}
+
 				onCurrentTextChanged: {
 					var curVendor
 					var curProduct

mobile-widgets/qml/main.qml

@@ -820,13 +820,21 @@ if you have network connectivity and want to sync your data to cloud storage."),
 		downloadFromDc.dcImportModel.clearTable()
 		if (vendor !== undefined && product !== undefined && connection !== undefined) {
 			downloadFromDc.setupUSB = true
-			/* set up the correct values on the download page */
+			// set up the correct values on the download page
-			if (vendor !== -1)
+			// setting the currentIndex to -1, first, helps to ensure
+			// that the comboBox does get updated in the UI
+			if (vendor !== -1) {
+				downloadFromDc.vendor = -1
 				downloadFromDc.vendor = vendor
-			if (product !== -1)
+			}
+			if (product !== -1) {
+				downloadFromDc.product = -1
 				downloadFromDc.product = product
-			if (connection !== -1)
+			}
+			if (connection !== -1) {
+				downloadFromDc.connection = -1
 				downloadFromDc.connection = connection
+			}
 		} else {
 			downloadFromDc.setupUSB = false
 		}