diff --git a/ide/main.pp b/ide/main.pp
index 4bf2c10638..1dd66f7337 100644
--- a/ide/main.pp
+++ b/ide/main.pp
@@ -5009,6 +5009,7 @@ begin
   PkgBoss.OpenProjectDependencies(Project1,true);
 
   Project1.DefineTemplates.AllChanged;
+  //DebugLn('TMainIDE.DoCompleteLoadingProjectInfo ',Project1.IDAsString);
   Project1.DefineTemplates.Active:=true;
   Result:=mrOk;
 end;
diff --git a/ide/project.pp b/ide/project.pp
index 9ada3ea3b4..87816ecc36 100644
--- a/ide/project.pp
+++ b/ide/project.pp
@@ -799,7 +799,7 @@ end;
 function TUnitInfo.CreateUnitName: string;
 begin
   Result:=UnitName;
-  if (Result='') and FilenameIsPascalUnit(Filename) then
+  if (Result='') and FilenameIsPascalSource(Filename) then
     Result:=ExtractFilenameOnly(Filename);
 end;
 
@@ -1093,7 +1093,7 @@ end;
 
 procedure TUnitInfo.UpdateSourceDirectoryReference;
 begin
-  FSourceDirNeedReference:=IsPartOfProject and (FilenameIsPascalUnit(Filename));
+  FSourceDirNeedReference:=IsPartOfProject and (FilenameIsPascalSource(Filename));
   if (not AutoReferenceSourceDir) or (FProject=nil) then exit;
   if FSourceDirNeedReference then begin
     if not SourceDirectoryReferenced then begin
diff --git a/lcl/include/control.inc b/lcl/include/control.inc
index c61e7f8d6d..fbebc52b8d 100644
--- a/lcl/include/control.inc
+++ b/lcl/include/control.inc
@@ -3121,11 +3121,12 @@ begin
   // create new float dock site and dock this control into it.
   if Result then begin
     FloatHost := CreateFloatingDockSite(TheScreenRect);
-    FloatHost.Visible := true;
     //debugln('TControl.ManualFloat A '+Name,':',ClassName,' ',dbgs(TheScreenRect),' FloatHost=',dbgs(FloatHost<>nil));
-    if FloatHost<>nil then
+    if FloatHost<>nil then  begin
+      // => dock this control into it.
+      FloatHost.Visible := true;
       Dock(FloatHost,Rect(0,0,FloatHost.ClientWidth,FloatHost.ClientHeight))
-    else
+    end else
       Dock(nil,TheScreenRect);
   end;
 end;
diff --git a/lcl/include/customsplitter.inc b/lcl/include/customsplitter.inc
index aeb08fa5b8..d8de01d037 100644
--- a/lcl/include/customsplitter.inc
+++ b/lcl/include/customsplitter.inc
@@ -507,7 +507,9 @@ begin
           // calculate how much the CurResizeControl can be enlarged
           CurMaxEnlarge:=Max(0,GetControlConstraintsMaxSize(CurResizeControl)
                          -GetControlSize(CurResizeControl));
-          //debugln('TCustomSplitter.MouseMove ',DbgSName(Self),' CurResizeControl=',DbgSName(CurResizeControl),' CurMaxShrink=',dbgs(CurMaxShrink),' CurMaxEnlarge=',dbgs(CurMaxEnlarge));
+          if CurMaxEnlarge=0 then
+            CurMaxEnlarge:=GetParentsClientSize;
+          //debugln('TCustomSplitter.MouseMove ',DbgSName(Self),' CurResizeControl=',DbgSName(CurResizeControl),' CurMaxShrink=',dbgs(CurMaxShrink),' CurMaxEnlarge=',dbgs(CurMaxEnlarge),' ',dbgs(GetControlConstraintsMaxSize(CurResizeControl)));
 
           // apply to the offset boundaries
           if (CurResizeControl.AnchorSide[akLeft].Control=Self)
diff --git a/lcl/ldockctrl.pas b/lcl/ldockctrl.pas
index 9365e2030a..8ff226dbc7 100644
--- a/lcl/ldockctrl.pas
+++ b/lcl/ldockctrl.pas
@@ -198,7 +198,7 @@ begin
 
     // enable Undock button, if Control is docked
     Dlg.UndockGroupBox.Enabled:=(Control.Parent<>nil)
-                                 and (Control.Parent<>Control.HostDockSite);
+                                 and (Control.Parent.ControlCount>1);
     
     if Dlg.ShowModal=mrOk then begin
       // dock or undock
diff --git a/lcl/ldocktree.pas b/lcl/ldocktree.pas
index 8ff2516bda..a2dbf32650 100644
--- a/lcl/ldocktree.pas
+++ b/lcl/ldocktree.pas
@@ -705,6 +705,7 @@ var
   i: Integer;
   CurControl: TControl;
 begin
+  DebugLn('TAnchoredDockManager.DeleteSideSplitter Splitter=',DbgSName(Splitter),' Side=',dbgs(ord(Side)),' NewAnchorControl=',DbgSName(NewAnchorControl));
   SplitterParent:=Splitter.Parent;
   SplitterParent.DisableAlign;
   try
@@ -771,6 +772,7 @@ var
   i: Integer;
   CurControl: TControl;
 begin
+  DebugLn('TAnchoredDockManager.CombineSpiralSplitterPair Splitter1=',DbgSName(Splitter1),dbgs(Splitter1.BoundsRect),' Splitter2=',DbgSName(Splitter2),dbgs(Splitter2.BoundsRect));
   // check splitters have the same Parent
   ParentControl:=Splitter1.Parent;
   if (ParentControl=nil) then
@@ -820,6 +822,7 @@ procedure TAnchoredDockManager.DeletePage(Page: TLazDockPage);
 var
   Pages: TLazDockPages;
 begin
+  DebugLn('TAnchoredDockManager.DeletePage Page=',DbgSName(Page));
   Pages:=Page.PageControl;
   Page.Free;
   if Pages.PageCount=0 then
@@ -828,6 +831,7 @@ end;
 
 procedure TAnchoredDockManager.DeletePages(Pages: TLazDockPages);
 begin
+  DebugLn('TAnchoredDockManager.DeletePages Pages=',DbgSName(Pages));
   if Pages.Parent<>nil then
     UndockControl(Pages,false);
   Pages.Free;
@@ -835,6 +839,7 @@ end;
 
 procedure TAnchoredDockManager.DeleteDockForm(ADockForm: TLazDockForm);
 begin
+  DebugLn('TAnchoredDockManager.DeleteDockForm ADockForm=',DbgSName(ADockForm));
   if ADockForm.Parent<>nil then
     UndockControl(ADockForm,false);
   ADockForm.Free;
@@ -923,6 +928,7 @@ var
   DropCtlPage: TLazDockPage;
   NewPageIndex: Integer;
   NewPage: TLazDockPage;
+  NewParent: TLazDockForm;
 begin
   if Control.Parent<>nil then
     RaiseGDBException('TAnchoredDockManager.InsertControl Control.Parent<>nil');
@@ -939,16 +945,25 @@ begin
 
       // make sure, there is a parent HostSite
       if DropCtl.Parent=nil then begin
-        DropCtl.FloatingDockSiteClass:=TLazDockForm;
-        DropCtl.ManualFloat(DropCtl.BoundsRect);
-        if DropCtl.Parent=nil then begin
-          RaiseGDBException('TAnchoredDockManager.InsertControl unable to create HostDockSite for DropCtl');
-        end;
+        // create a TLazDockForm as new parent
+        NewParent:=TLazDockForm.Create(Application);
+        NewParent.BoundsRect:=DropCtl.BoundsRect;
+        DropCtl.Parent:=NewParent;
         // init anchors of DropCtl
         DropCtl.Align:=alNone;
         for a:=Low(TAnchorKind) to High(TAnchorKind) do
           DropCtl.AnchorParallel(a,0,DropCtl.Parent);
         DropCtl.Anchors:=[akLeft,akTop,akRight,akBottom];
+        NewParent.Visible:=true;
+        //DebugLn('TAnchoredDockManager.DockControl DropCtl=',DbgSName(DropCtl),' NewParent.BoundsRect=',dbgs(NewParent.BoundsRect));
+      end else begin
+        if (DropCtl.Parent is TLazDockForm) then begin
+          // ok
+        end else if (DropCtl.Parent is TLazDockPage) then begin
+          // ok
+        end else begin
+          RaiseGDBException('TAnchoredDockManager.InsertControl DropCtl has invalid parent');
+        end;
       end;
 
       DropCtl.Parent.DisableAlign;
@@ -1167,9 +1182,14 @@ var
   procedure DoFinallyForParent;
   var
     OldParentControl: TWinControl;
+    NewBounds: TRect;
+    NewOrigin: TPoint;
   begin
     if Float then begin
-      Control.ManualFloat(Control.BoundsRect);
+      NewBounds:=Control.BoundsRect;
+      NewOrigin:=Control.ControlOrigin;
+      OffsetRect(NewBounds,NewOrigin.X,NewOrigin.Y);
+      Control.ManualFloat(NewBounds);
     end else begin
       Control.Parent:=nil;
     end;
@@ -1214,6 +1234,7 @@ begin
               // => this splitter is needed, can not be deleted.
               break;
             end;
+            dec(i);
           end;
           if i<0 then begin
             // this splitter is not needed anymore