Let BALM::{X|Y}Tabs be in multiple BALMLayouts, if they are friendly.

headers/libs/alm/ALMLayout.h

@@ -151,6 +151,17 @@ private:
 								BALMLayout(const BALMLayout&);
 			void				operator =(const BALMLayout&);
 
+	struct XTabRemover;
+	struct XTabRemoverFunc;
+
+	struct YTabRemover;
+	struct YTabRemoverFunc;
+
+	friend struct XTabRemover;
+	friend struct XTabRemoverFunc;
+
+	friend struct YTabRemover;
+	friend struct YTabRemoverFunc;
 
 	friend class XTab;
 	friend class YTab;
@@ -159,6 +170,9 @@ private:
 			float				InsetForTab(XTab* tab) const;
 			float				InsetForTab(YTab* tab) const;
 
+			void				_RemoveSelfFromTab(XTab* tab);
+			void				_RemoveSelfFromTab(YTab* tab);
+
 			BLayoutItem*		_LayoutItemToAdd(BView* view);
 
 			void				_UpdateAreaConstraints();

headers/libs/alm/Tab.h

@@ -29,7 +29,14 @@ protected:
 								XTab(BALMLayout* layout);
 
 private:
-			BALMLayout*			fALMLayout;
+			struct BALMLayoutList;
+
+			bool				IsInLayout(BALMLayout* layout);
+			bool				AddedToLayout(BALMLayout* layout);
+			void				LayoutLeaving(BALMLayout* layout);
+			bool				IsSuitableFor(BALMLayout* layout);
+
+			BALMLayoutList*		fLayouts;
 
 			uint32				_reserved[2];
 };
@@ -44,7 +51,12 @@ protected:
 								YTab(BALMLayout* layout);
 
 private:
-			BALMLayout*			fALMLayout;
+			bool				IsInLayout(BALMLayout* layout);
+			bool				AddedToLayout(BALMLayout* layout);
+			void				LayoutLeaving(BALMLayout* layout);
+			bool				IsSuitableFor(BALMLayout* layout);
+
+			XTab::BALMLayoutList* fLayouts;
 
 			uint32				_reserved[2];
 };