Fix Sheet failing to block events for native components behind it

CodenameOne/src/com/codename1/ui/Sheet.java

@@ -478,7 +478,41 @@ public void paint(Graphics g, Rectangle rect) {
             cnt.revalidate();
 
         }
-        if (cnt.getComponentCount() > 0) {
+        boolean foundSheet = false;
+        Component blocker = null;
+        for (Component child : cnt) {
+            if (child instanceof Sheet) {
+                foundSheet = true;
+            } else if (Boolean.TRUE.equals(child.getClientProperty("SheetBlocker"))) {
+                blocker = child;
+            }
+        }
+
+        boolean needsBlocker = Form.activePeerCount > 0;
+        if (needsBlocker) {
+            if (blocker == null) {
+                blocker = new Button();
+                blocker.putClientProperty("SheetBlocker", Boolean.TRUE);
+                blocker.setUIID("Container");
+                blocker.getAllStyles().setBgTransparency(0);
+                int size = Math.max(CN.getDisplayWidth(), CN.getDisplayHeight()) * 2;
+                blocker.setPreferredSize(new com.codename1.ui.geom.Dimension(size, size));
+                ((Button) blocker).addActionListener(new ActionListener() {
+                    @Override
+                    public void actionPerformed(ActionEvent evt) {
+                        hide(duration);
+                    }
+                });
+                cnt.addComponent(0, BorderLayout.CENTER, blocker);
+            }
+        } else {
+            if (blocker != null) {
+                cnt.removeComponent(blocker);
+                blocker = null;
+            }
+        }
+
+        if (foundSheet) {
             $(".Sheet", cnt).each(new ComponentClosure() {
                 @Override
                 public void call(Component c) {
@@ -514,8 +548,18 @@ public void call(Component c) {
                 }
 
             });
-            Component existing = cnt.getComponentAt(0);
-            cnt.replace(existing, this, null);
+            Component existing = null;
+            for(Component c : cnt) {
+                if (c instanceof Sheet) {
+                    existing = c;
+                    break;
+                }
+            }
+            if (existing != null) {
+                cnt.replace(existing, this, null);
+            } else {
+                cnt.add(getPosition(), this);
+            }
             cnt.animateLayout(duration);
         } else {
             cnt.add(getPosition(), this);

scripts/hellocodenameone/common/src/main/java/com/codenameone/examples/hellocodenameone/tests/BrowserComponentScreenshotTest.java

@@ -2,6 +2,8 @@
 
 import com.codename1.ui.BrowserComponent;
 import com.codename1.ui.Form;
+import com.codename1.ui.Label;
+import com.codename1.ui.Sheet;
 import com.codename1.ui.layouts.BorderLayout;
 import com.codename1.ui.util.UITimer;
 import com.codename1.util.SuccessCallback;
@@ -56,6 +58,10 @@ public void onSucess(BrowserComponent.JSRef result) {
             return;
         }
 
+        Sheet sheet = new Sheet(null, "Overlay Sheet");
+        sheet.getContentPane().add(new Label("This is a sheet covering part of the browser"));
+        sheet.show(0);
+
         UITimer.timer(2000, false, form, readyRunnable);
         readyRunnable = null;
     }

scripts/hellocodenameone/common/src/main/kotlin/com/codenameone/examples/hellocodenameone/tests/KotlinUiTest.kt

@@ -3,18 +3,19 @@ package com.codenameone.examples.hellocodenameone.tests
 import com.codename1.components.Accordion
 import com.codename1.components.MultiButton
 import com.codename1.components.Switch
-import com.codename1.ui.Button
-import com.codename1.ui.CheckBox
-import com.codename1.ui.Container
-import com.codename1.ui.Label
-import com.codename1.ui.Slider
-import com.codename1.ui.TextArea
-import com.codename1.ui.TextField
+import com.codename1.testing.TestUtils
+import com.codename1.ui.*
 import com.codename1.ui.layouts.BoxLayout
 
 class KotlinUiTest : BaseTest() {
     override fun runTest(): Boolean {
-        val kotlinForm = createForm("Kotlin", BoxLayout.y(), "kotlin")
+        var called = BooleanArray(1)
+        val kotlinForm =  object : Form("Kotlin", BoxLayout.y()) {
+            override fun onShowCompleted() {
+                super.onShowCompleted()
+                called[0] = true
+            }
+        }
         kotlinForm.addAll(
                 Label("Kotlin UI Test Components"),
                 Button("Kotlin Button"),
@@ -51,6 +52,21 @@ class KotlinUiTest : BaseTest() {
 
         kotlinForm.add(accordion)
         kotlinForm.show()
+
+        val sheet = Sheet(null, "Overlay Sheet")
+        sheet.contentPane.add(Label("This is a sheet covering part of the screen"))
+        sheet.show(0)
+
+        var timeout = 100;
+        while (sheet.parent == null && !called[0]) {
+            TestUtils.waitFor(10)
+            timeout--
+            TestUtils.assertNotEqual(0, timeout)
+        }
+
+        Cn1ssDeviceRunnerHelper.emitCurrentFormScreenshot("kotlin")
+        done()
+
         return true
     }
 }