diff --git a/components/chmhelp/lhelp/lhelpcore.pas b/components/chmhelp/lhelp/lhelpcore.pas
index 8576082d73..49dc0ffc94 100644
--- a/components/chmhelp/lhelp/lhelpcore.pas
+++ b/components/chmhelp/lhelp/lhelpcore.pas
@@ -109,6 +109,11 @@ type
     fConfig: TXMLConfig;
     fHasShowed: Boolean;
     fHide: boolean; //If yes, start with content hidden. Otherwise start normally
+    // Keep track of whether size/position preferences were loaded and applied to form
+    fLayoutApplied: boolean;
+    // Applies layout (size/position/fullscreen) preferences once in lhelp lifetime
+    // Needs LoadPreference to be run first to get fConfig object.
+    procedure ApplyLayoutPreferencesOnce;
     // Load preferences. Preferences are unique for server-lhelp pairs and plain lhelp
     procedure LoadPreferences(AIPCName: String);
     // Saves preferences. Uses existing config loaded by LoadPreferences
@@ -163,6 +168,9 @@ implementation
 uses 
   LHelpControl;
 
+const
+  DigitsInPID=5; // Number of digits in the formatted PID according to the Help Protocol
+
 type
   TRecentMenuItem = class(TMenuItem)
   public
@@ -362,6 +370,29 @@ begin
   RefreshState;
 end;
 
+procedure THelpForm.ApplyLayoutPreferencesOnce;
+begin
+  if not(assigned(fConfig)) then exit;
+  if (not(fHide)) and
+    (not(fLayoutApplied)) then
+  begin
+    if (fConfig.GetValue('Position/Maximized', false)=true) then
+    begin
+      Windowstate:=wsMaximized
+    end
+    else
+    begin
+      Left   := fConfig.GetValue('Position/Left/Value', Left);
+      Top    := fConfig.GetValue('Position/Top/Value', Top);
+      Width  := fConfig.GetValue('Position/Width/Value', Width);
+      Height := fConfig.GetValue('Position/Height/Value', Height);
+    end;
+    // Keep track so we do not reapply initial settings as user may have
+    // changed size etc in the meantime.
+    fLayoutApplied := true;
+  end;
+end;
+
 procedure THelpForm.ViewMenuContentsClick(Sender: TObject);
 begin
   // TabsControl property in TChmContentProvider
@@ -388,29 +419,16 @@ begin
   ForceDirectoriesUTF8(PrefFile);
   // --ipcname passes a server ID that consists of a
   // server-dependent constant together with a process ID.
-  // Strip out the process ID to get fixed config file names for one server
-  ServerPart := Copy(AIPCName, 1, length(AIPCName)-5); //strip out PID
+  // Strip out the formatted process ID to get fixed config file names for
+  // one server
+  ServerPart := Copy(AIPCName, 1, length(AIPCName)-DigitsInPID);
   PrefFile := Format('%slhelp-%s.conf',[IncludeTrailingPathDelimiter(PrefFile), ServerPart]);
 
   fConfig := TXMLConfig.Create(Self);
   fConfig.Filename := PrefFile;
 
   // Restore window but only if currently not being asked to hide
-  if not(fHide) then
-  begin
-    if (fConfig.GetValue('Position/Maximized',false)=true) then
-    begin
-      Windowstate:=wsMaximized
-    end
-    else
-    begin
-      Left   := fConfig.GetValue('Position/Left/Value', Left);
-      Top    := fConfig.GetValue('Position/Top/Value', Top);
-      Width  := fConfig.GetValue('Position/Width/Value', Width);
-      Height := fConfig.GetValue('Position/Height/Value', Height);
-    end;
-  end;
-
+  ApplyLayoutPreferencesOnce;
   OpenDialog1.FileName := fConfig.GetValue('LastFileOpen/Value', OpenDialog1.FileName);
 
   RecentCount:= fConfig.GetValue('Recent/ItemCount/Value', 0);
@@ -427,6 +445,7 @@ begin
     exit; //silently abort
   if not (WindowState = wsMaximized) then
   begin
+    fConfig.SetValue('Position/Maximized', false);
     fConfig.SetValue('Position/Left/Value', Left);
     fConfig.SetValue('Position/Top/Value', Top);
     fConfig.SetValue('Position/Width/Value', Width);
@@ -616,6 +635,9 @@ begin
       Self.SendToBack;
       Self.BringToFront;
       Self.ShowOnTop;
+      // If lhelp was run with hidden parameter, we need to apply
+      // layout preferences once:
+      ApplyLayoutPreferencesOnce;
     end;
   end;
 end;
diff --git a/components/chmhelp/packages/idehelp/lazchmhelp.pas b/components/chmhelp/packages/idehelp/lazchmhelp.pas
index 3090ec459b..54b82cbeb7 100644
--- a/components/chmhelp/packages/idehelp/lazchmhelp.pas
+++ b/components/chmhelp/packages/idehelp/lazchmhelp.pas
@@ -63,6 +63,7 @@ type
     procedure SetHelpEXE(AValue: String);
   protected
     function GetFileNameAndURL(RawUrl: String; out FileName: String; out URL: String): Boolean;
+    // Sets label/ID used for simpleipc communications
     procedure SetHelpLabel(AValue: String);
     // Check for lhelp executable, if not present, build if possible
     function CheckBuildLHelp: Integer; // modal result
@@ -112,12 +113,15 @@ const
   // Part of help name. Stored/retrieved in Lazarus options CHMHelp/Name.
   // Do not localize.
   CHMHelpName='lazhelp';
+  DigitsInPID=5; // Number of digits in the formatted PID according to the Help Protocol
 
 // Formats (part of) process ID according to help protocol for
 // use in ipcname parameter
 function HelpProtocolFormattedPID: string;
 begin
-  result := copy(inttostr(GetProcessID)+'00000',1,5)
+  // Make sure at least DigitsInPID digits present even if 0
+  result := copy(inttostr(GetProcessID)+
+    StringOfChar('0',DigitsInPID),1,DigitsInPID)
 end;
 
 procedure Register;
@@ -149,8 +153,7 @@ function TChmHelpViewer.GetHelpLabel: String;
 begin
   // fHelpLabel is used for SimpleIPC server id;
   // lhelp protocol specifies server-dependent constant string
-  // followed by string representation of last 5 digits of the processID
-  // padded with 00000 at the right
+  // followed by formatted string representation of (part of) processid/PID
   // Autocalculate if needed:
   if Length(fHelpLabel) = 0 then
     fHelpLabel := CHMHelpName + HelpProtocolFormattedPID;
@@ -280,21 +283,22 @@ begin
     if not (fHelpLabel[i] in ['a'..'z', '0'..'9', 'A'..'Z']) then
       fHelpLabel[i] := '_';
   end;
-  // todo: for some reason we get assigned strings like
+  // Validity check for labels like
   // lazhelp501204548
-  // i.e. with too many numbers in the PID part
-  // Hacky way to fix this: if too many numbers, replace with
-  // default
+  // i.e. with too many numbers in the PID part.
+  // These may be left over in option files from earlier Lazarus versions.
+  // If too many numbers at end, replace with default
   if fHelpLabel[length(FHelpLabel)] in ['0'..'9'] then
   begin
     for i := Length(fHelpLabel) downto 1 do
     begin
       if not(fHelpLabel[i] in ['0'..'9']) then
       begin
-        if (Length(fHelpLabel)-i>5) then
+        if (Length(fHelpLabel)-i>DigitsInPID) then
         begin
           Debugln('TChmHelpViewer.SetHelpLabel: got '+fHelpLabel+'. Help protocol does not allow this many digits. Resetting to empty string.');
-          fHelpLabel := '';
+          // Revert to default
+          fHelpLabel := CHMHelpName + HelpProtocolFormattedPID;
         end;
         break;
       end;
@@ -557,14 +561,14 @@ begin
     if Trim(fHelpExeParams) = '' then
     begin
       Result := shrViewerError;
-      ErrMsg := 'If you do not use "lhelp" as viewer you have to set up '
-              + 'HelpExeParams correctly in' + sLineBreak
-              + 'Tools -> Options -> Help -> Help Options -> '
-              + 'under HelpViewers - CHM Help Viewer' + sLineBreak
-              + 'e.g. for HH.EXE (HTML Help in Windows) it must be' + sLineBreak
-              + '  "%s::%s"' + sLineBreak
-              + 'where first %s will be replaced by CHM file name' + sLineBreak
-              + 'and the second one will be replaced by URL';
+      ErrMsg := 'If you do not use "lhelp" as viewer you have to set up ' +
+        'HelpExeParams correctly in' + LineEnding +
+        'Tools -> Options -> Help -> Help Options -> ' +
+        'under HelpViewers - CHM Help Viewer' + LineEnding +
+        'e.g. for HH.EXE (HTML Help in Windows) it must be' + LineEnding +
+        '  "%s::%s"' + LineEnding +
+        'where first %s will be replaced by CHM file name' + LineEnding +
+        'and the second one will be replaced by URL';
       Exit;
     end;