fix #1023 MultiSelect DropDown appears in center and therefore detached from its inputfield if too little space available

Author: vegegoku

domino-ui/src/main/java/org/dominokit/domino/ui/menu/direction/DropDirection.java

@@ -15,11 +15,13 @@
  */
 package org.dominokit.domino.ui.menu.direction;
 
+import static org.dominokit.domino.ui.menu.MenuStyles.dui_menu;
 import static org.dominokit.domino.ui.utils.Domino.elementOf;
 
 import elemental2.dom.Element;
 import elemental2.dom.Event;
 import org.dominokit.domino.ui.style.CssClass;
+import org.dominokit.domino.ui.utils.DominoElement;
 
 /** DropDirection interface. */
 public interface DropDirection {
@@ -50,12 +52,19 @@ default void cleanup(Element source) {}
   default void cleanSelf(Element source) {}
 
   default DropDirection fallBackPosition(DropDirectionContext context, SpaceChecker spaceChecker) {
-    elementOf(context.getSource()).setCssProperty(spaceChecker.getMaximumSideSpaceProperty());
-    elementOf(context.getSource()).setCssProperty(spaceChecker.getMaximumVerticalSpaceProperty());
+    DominoElement<Element> source = elementOf(context.getSource());
+    if (dui_menu.isAppliedTo(context.getSource())
+        && !source.hasAttribute("dui-position-fallback")) {
+      source.setCssProperty(spaceChecker.getMaximumSideSpaceProperty());
+      source.setCssProperty(spaceChecker.getMaximumVerticalSpaceProperty());
 
-    context.newSpaceChecker();
+      context.newSpaceChecker();
 
-    return position(context);
+      DropDirection position = position(context);
+      source.setAttribute("dui-position-fallback", true);
+      return position;
+    }
+    return MIDDLE_SCREEN.position(context);
   }
 
   /** Constant <code>BEST_FIT_SIDE</code> */

domino-ui/src/main/java/org/dominokit/domino/ui/menu/direction/SpaceChecker.java

@@ -226,11 +226,11 @@ public double getSourceBottom() {
   }
 
   public double getMaximumSideSpace() {
-    return Math.max(getAvailableSpaceOnLeft(), getAvailableSpaceOnRight());
+    return Math.min(sourceWidth, Math.max(getAvailableSpaceOnLeft(), getAvailableSpaceOnRight()));
   }
 
   public double getMaximumVerticalSpace() {
-    return Math.max(getAvailableSpaceOnTop(), getAvailableSpaceOnBottom());
+    return Math.min(sourceHeight, Math.max(getAvailableSpaceOnTop(), getAvailableSpaceOnBottom()));
   }
 
   public CssProperty getMaximumSideSpaceProperty() {

domino-ui/src/main/java/org/dominokit/domino/ui/popover/Popover.java

@@ -234,6 +234,19 @@ public Popover setModal(boolean modal) {
     return this;
   }
 
+  @Override
+  public ZIndexLayer getZIndexLayer() {
+    if (isModal()) {
+      return ZIndexLayer.Z_LAYER_3;
+    }
+    return super.getZIndexLayer();
+  }
+
+  @Override
+  public boolean incrementsZIndex() {
+    return isModal();
+  }
+
   /**
    * {@inheritDoc}
    *