v1.4.0: digit-only flaps with white euro text, nixie white euro + configurable flicker, mode-conditional config fields; fix stale derived-property reads in change handler

contents/ui/DisplayFlip.qml

@@ -1,7 +1,9 @@
 /*
  * Split-flap display mode — airport departure board style.
- * White characters on black cells with a flap split line;
- * changed characters flip with a cascading animation.
+ * Only digits are shown as flaps; the euro sign is rendered as plain
+ * text (default font, white) next to the board, and the trend shows
+ * on a small LED. Changed characters flip with a cascading animation
+ * spread over the configured number of seconds.
  * Pure QtQuick so it can be tested outside the plasmoid shell.
  */
 
@@ -18,6 +20,23 @@ Row {
 
     spacing: height * 0.06
 
+    function digitsOf(s) {
+        var out = "";
+        for (var i = 0; i < s.length; i++) {
+            var ch = s.charAt(i);
+            if ((ch >= "0" && ch <= "9") || ch === "-") {
+                out += ch;
+            }
+        }
+        return out;
+    }
+
+    // UI-only derived values (euro visibility); logic must not rely on these —
+    // QML gives no ordering guarantee between a change handler and the
+    // re-evaluation of dependent bindings.
+    readonly property string digitsOnly: digitsOf(display)
+    readonly property string boardText: digitsOnly.length > 0 ? digitsOnly : "--"
+
     property var chars: []
     property bool ready: false
     readonly property real cellFont: height * 0.72
@@ -26,7 +45,7 @@ Row {
     readonly property int flapDuration: 260
 
     Component.onCompleted: {
-        chars = display.split("");
+        chars = boardText.split("");
         ready = true;
     }
 
@@ -34,7 +53,10 @@ Row {
         if (!ready) {
             return;
         }
-        var nc = display.split("");
+        // compute from display directly: derived bindings may still be
+        // stale at this point (QML makes no ordering guarantee)
+        var digits = digitsOf(display);
+        var nc = (digits.length > 0 ? digits : "--").split("");
         var n = Math.max(chars.length, nc.length);
         // spread the changed cells evenly across flapSeconds
         var changed = [];
@@ -141,8 +163,17 @@ Row {
         }
     }
 
-    // trend LED (green/red/grey) — boards are monochrome, so the
-    // trend shows here instead of in the letter color
+    // euro sign in the plain-text font, white
+    Text {
+        anchors.verticalCenter: parent.verticalCenter
+        text: "\u20AC"
+        visible: root.digitsOnly.length > 0
+        color: "#ffffff"
+        font.family: Qt.application.font.family
+        font.pixelSize: root.height * 0.66
+    }
+
+    // trend LED (green/red/grey)
     Rectangle {
         width: root.height * 0.14
         height: width