Added new Action GUI class (and tests).

* NEW: Added new Action GUI type.
* NEW: Added testing implementation of ConfirmDeleteMapGui.
* BUG: Newly opened GUIs are now correctly registered.
* BUG: GUI: Fixed NPE when first generating the inventory.
* BUG: GUIs opened from another GUI do not interfere anymore when
  the parent GUI is closed.

src/main/java/fr/moribus/imageonmap/gui/list/MapDetailGui.java

@@ -20,6 +20,7 @@ package fr.moribus.imageonmap.gui.list;
 
 import fr.moribus.imageonmap.gui.core.AbstractGui;
 import fr.moribus.imageonmap.gui.core.GuiManager;
+import fr.moribus.imageonmap.guiproko.core.Gui;
 import fr.moribus.imageonmap.map.ImageMap;
 import fr.moribus.imageonmap.map.PosterMap;
 import fr.moribus.imageonmap.ui.MapItemManager;
@@ -266,6 +267,7 @@ public class MapDetailGui extends AbstractGui
 
 			case "delete":
 				GuiManager.openGui(player, new ConfirmDeleteMapGui(map, currentPage));
+                            //Gui.open(player, new fr.moribus.imageonmap.guiproko.list.ConfirmDeleteMapGui());
 				return;
 
 			default:

src/main/java/fr/moribus/imageonmap/guiproko/core/ActionGui.java

@@ -0,0 +1,138 @@
+/*
+ * Copyright (C) 2013 Moribus
+ * Copyright (C) 2015 ProkopyL <prokopylmc@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package fr.moribus.imageonmap.guiproko.core;
+
+import fr.moribus.imageonmap.PluginLogger;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import org.bukkit.Material;
+import org.bukkit.event.inventory.InventoryClickEvent;
+import org.bukkit.inventory.Inventory;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.meta.ItemMeta;
+
+abstract public class ActionGui extends Gui
+{
+    static private final String ACTION_HANDLER_NAME = "action_";
+    private final Class<? extends ActionGui> guiClass = this.getClass();
+    private final HashMap<Integer, Action> actions = new HashMap<>();
+    private int maxSlot;
+    
+    /* ===== Protected API ===== */
+    
+    protected void action(String name, int slot, Material material, String title, String ... loreLines)
+    {
+        action(name, slot, new ItemStack(material), title, Arrays.asList(loreLines));
+    }
+    
+    protected void action(String name, int slot, ItemStack item, String title, String ... loreLines)
+    {
+        action(name, slot, item, title, Arrays.asList(loreLines));
+    }
+    
+    protected void action(String name, int slot, ItemStack item, String title, List<String> loreLines)
+    {
+        ItemMeta meta = item.getItemMeta();
+        meta.setDisplayName(title);
+        meta.setLore(loreLines);
+        item.setItemMeta(meta);
+        
+        Method callback;
+        try
+        {
+            callback = guiClass.getDeclaredMethod(ACTION_HANDLER_NAME + name);
+            callback.setAccessible(true);
+        }
+        catch (Throwable ex)
+        {
+            callback = null;
+        }
+        
+        if(slot > getSize() || slot < 0) 
+            throw new IllegalArgumentException("Illegal slot ID");
+        
+        action(new Action(name, slot, item, callback));
+    }
+    
+    private void action(Action action)
+    {
+        actions.put(action.slot, action);
+        if(maxSlot < action.slot) maxSlot = action.slot;
+    }
+    
+    @Override
+    protected abstract void onUpdate();
+    
+    @Override
+    public void update()
+    {
+        actions.clear();
+        super.update();
+    }
+    
+    @Override
+    protected void populate(Inventory inventory)
+    {
+        for(Action action : actions.values())
+        {
+            inventory.setItem(action.slot, action.item);
+        }
+    }
+
+    @Override
+    protected void onClick(InventoryClickEvent event)
+    {
+        event.setCancelled(true);
+        
+        Action action = actions.get(event.getRawSlot());
+        if(action == null || action.callback == null) return;
+        try
+        {
+            action.callback.invoke(this);
+        }
+        catch (IllegalAccessException | IllegalArgumentException ex)
+        {
+            PluginLogger.error("Could not invoke GUI action handler", ex);
+        }
+        catch (InvocationTargetException ex)
+        {
+            PluginLogger.error("Error while invoking action handler {0} of GUI {1}", ex, action.name, guiClass.getName());
+        }
+    }
+    
+    
+    static private class Action
+    {
+        public String name;
+        public int slot;
+        public ItemStack item;
+        public Method callback;
+        
+        public Action(String name, int slot, ItemStack item, Method callback)
+        {
+            this.name = name;
+            this.slot = slot;
+            this.item = item;
+            this.callback = callback;
+        }
+    }
+}

src/main/java/fr/moribus/imageonmap/guiproko/core/Gui.java

@@ -66,9 +66,10 @@ abstract public class Gui
     private void open(HumanEntity player)
     {
         this.player = player;
+        openGuis.put(player, this);
         update();
-        this.open = true;
         player.openInventory(inventory);
+        this.open = true;
     }
     
     /* ===== Public API ===== */
@@ -81,8 +82,13 @@ abstract public class Gui
     {
         onUpdate();
         
-        //If inventory needs to be regenerated
+        //If inventory does not need to be regenerated
         if(inventory != null && inventory.getTitle().equals(title) && inventory.getSize() == size)
+        {
+            inventory.clear();
+            populate(inventory);
+        }
+        else
         {
             inventory = Bukkit.createInventory(player, size, title);
             populate(inventory);
@@ -92,11 +98,6 @@ abstract public class Gui
                 player.openInventory(inventory);
             }
         }
-        else
-        {
-            inventory.clear();
-            populate(inventory);
-        }
     }
     
     /**
@@ -250,6 +251,7 @@ abstract public class Gui
             HumanEntity owner = event.getPlayer();
             Gui openGui = openGuis.get(owner);
             if(openGui == null) return;
+            if(!openGui.isOpen()) return;
             
             openGui.onClose();
             openGuis.remove(owner);

src/main/java/fr/moribus/imageonmap/guiproko/list/ConfirmDeleteMapGui.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2013 Moribus
+ * Copyright (C) 2015 ProkopyL <prokopylmc@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package fr.moribus.imageonmap.guiproko.list;
+
+import fr.moribus.imageonmap.guiproko.core.ActionGui;
+import org.bukkit.Material;
+
+public class ConfirmDeleteMapGui extends ActionGui
+{
+    @Override
+    protected void onUpdate()
+    {
+        setTitle("Are you sure ?");
+        setSize(2);
+        
+        action("toto", 1, Material.DIAMOND, "Toto");
+        action("tata", 2, Material.EMERALD, "Tata");
+    }
+    
+    protected void action_toto()
+    {
+        getPlayer().sendMessage("toto");
+    }
+    
+    protected void action_tata()
+    {
+        getPlayer().sendMessage("tata");
+    }
+}