Implement event model in C++

Filtering events in JS is too slow with >20,000 events. This moves the
event data model into C++.

Fields/Text.qml

@@ -6,11 +6,11 @@ import QtQuick.Controls 2.13
 Label {
     id: control
 
-    property var definition
+    property var model
     property alias value: control.text
 
     Keys.onPressed: {
-        if (event.text === definition.key) {
+        if (event.text === model.key) {
             popup.open()
             event.accepted = true
         }
@@ -23,8 +23,8 @@ Label {
     Popup {
         id: popup
 
-        width: control.width
-        height: control.height
+        width: parent.width
+        height: parent.height
         padding: 0
 
         onOpened: {