qml: add simple Toaster, mainly to indicate copy to clipboard

electrum/gui/qml/components/controls/Toaster.qml

@@ -0,0 +1,57 @@
+import QtQuick 2.6
+import QtQuick.Layouts 1.0
+import QtQuick.Controls 2.14
+import QtQuick.Controls.Material 2.0
+
+import ".."
+
+Item {
+    id: toaster
+    width: rect.width
+    height: rect.height
+    visible: false
+
+    property int _y
+    property string _text
+
+    function show(item, text) {
+        _text = text
+        var r = item.mapToItem(parent, item.x, item.y)
+        x = r.x
+        y = r.y - toaster.height - constants.paddingLarge
+        toaster._y = y - 35
+        ani.restart()
+    }
+
+    SequentialAnimation {
+        id: ani
+        running: false
+        PropertyAction { target: toaster; property: 'visible'; value: true }
+        PropertyAction { target: toaster; property: 'opacity'; value: 1 }
+        PauseAnimation { duration: 1000}
+        ParallelAnimation {
+            NumberAnimation { target: toaster; property: 'y'; to: toaster._y; duration: 1000; easing.type: Easing.InQuad }
+            NumberAnimation { target: toaster; property: 'opacity'; to: 0; duration: 1000 }
+        }
+        PropertyAction { target: toaster; property: 'visible'; value: false }
+    }
+
+    Rectangle {
+        id: rect
+        width: contentItem.width
+        height: contentItem.height
+        color: constants.colorAlpha(Material.dialogColor, 0.90)
+        border {
+            color: Material.accentColor
+            width: 1
+        }
+
+        RowLayout {
+            id: contentItem
+            Label {
+                Layout.margins: 10
+                text: toaster._text
+            }
+        }
+    }
+}