Add WatchDiv demo

orx-panel/src/main/kotlin/org/openrndr/panel/elements/WatchDiv.kt

@@ -5,12 +5,13 @@ import kotlinx.coroutines.yield
 import org.openrndr.draw.Drawer
 import org.openrndr.launch
 
-class WatchDiv<T : Any>(val watchList: List<T>, val builder: WatchDiv<T>.(T) -> Unit) : Div(), DisposableElement {
+class WatchDiv<T : Any>(private val watchList: List<T>, private val builder: WatchDiv<T>.(T) -> Unit) : Div(), DisposableElement {
     override var disposed: Boolean = false
-    var listState = emptyList<T>()
-    var watchJob : Job? = null
+    private var listState = emptyList<T>()
+    private var watchJob: Job? = null
 
     override fun dispose() {
+        super.dispose()
         for (child in children) {
             child.parent = null
             (child as? DisposableElement)?.dispose()
@@ -18,7 +19,7 @@ class WatchDiv<T : Any>(val watchList: List<T>, val builder: WatchDiv<T>.(T) ->
         children.clear()
     }
 
-    private fun regenerate() {
+    fun regenerate() {
         var regenerate = false
         if (listState.size != watchList.size) {
             regenerate = true
@@ -45,7 +46,7 @@ class WatchDiv<T : Any>(val watchList: List<T>, val builder: WatchDiv<T>.(T) ->
         }
     }
 
-    override fun draw(drawer: Drawer) {
+    fun checkJob() {
         if (watchJob == null) {
             watchJob = (root() as Body).controlManager.program.launch {
                 while (!disposed) {
@@ -54,6 +55,9 @@ class WatchDiv<T : Any>(val watchList: List<T>, val builder: WatchDiv<T>.(T) ->
                 }
             }
         }
+    }
+    override fun draw(drawer: Drawer) {
+        checkJob()
         super.draw(drawer)
     }
 }
@@ -62,4 +66,6 @@ fun <T : Any> Element.watchDiv(vararg classes: String, watchList: List<T>, build
     val wd = WatchDiv(watchList, builder)
     wd.classes.addAll(classes.map { ElementClass(it) })
     this.append(wd)
+    wd.regenerate()
+    wd.checkJob()
 }