qml: handle android back button in wizard, map to prev page action instead of closing wizard.

Also add initial focus to WCHaveSeed and WCHaveMasterKey wizard components.

electrum/gui/qml/components/wizard/WCHaveMasterKey.qml

@@ -114,7 +114,6 @@ WizardComponent {
                 Layout.fillWidth: true
                 Layout.minimumHeight: 80
                 font.family: FixedFont
-                focus: true
                 wrapMode: TextEdit.WrapAnywhere
                 onTextChanged: {
                     if (activeFocus)
@@ -194,5 +193,6 @@ WizardComponent {
                 cosigner = wizard_data['multisig_current_cosigner']
             participants = wizard_data['multisig_participants']
         }
+        Qt.callLater(masterkey_ta.forceActiveFocus)
     }
 }

electrum/gui/qml/components/wizard/WCHaveSeed.qml

@@ -241,6 +241,7 @@ WizardComponent {
                 cosigner = wizard_data['multisig_current_cosigner']
         }
         setSeedTypeHelpText()
+        Qt.callLater(seedtext.forceActiveFocus)
     }
 
 }

electrum/gui/qml/components/wizard/Wizard.qml

@@ -15,6 +15,10 @@ ElDialog {
     title: wizardTitle + (pages.currentItem.title ? ' - ' + pages.currentItem.title : '')
     iconSource: '../../../icons/electrum.png'
 
+    // android back button triggers close() on Popups. Disabling close here,
+    // we handle that via Keys.onReleased event handler in the root layout.
+    closePolicy: Popup.NoAutoClose
+
     property string wizardTitle
 
     property var wizard_data
@@ -86,6 +90,14 @@ ElDialog {
         anchors.fill: parent
         spacing: 0
 
+        // root Item in Wizard, capture back button here and delegate to main
+        Keys.onReleased: {
+            if (event.key == Qt.Key_Back) {
+                console.log("Back button within wizard")
+                app.close() // this handles unwind of dialogs/stack
+            }
+        }
+
         SwipeView {
             id: pages
             Layout.fillWidth: true

electrum/gui/qml/components/wizard/WizardComponent.qml

@@ -1,6 +1,7 @@
 import QtQuick 2.0
 
 Item {
+    id: root
     signal next
     signal prev
     signal accept
@@ -28,6 +29,10 @@ Item {
         // wizard_data keys if apply() depends on variables set in descendant
         // Component.onCompleted handler.
         Qt.callLater(checkIsLast)
+
+        // move focus to root of WizardComponent, otherwise Android back button
+        // might be missed in Wizard root Item.
+        root.forceActiveFocus()
     }
 
 }