Fixed dock-able panels not restoring for mono instances

The bug happens when Notepad++ is in the tray, and is restored via mono instance restore mechanism.

Fixes #9454, close #12817

PowerEditor/src/NppBigSwitch.cpp

@@ -2480,6 +2480,33 @@ LRESULT Notepad_plus::process(HWND hwnd, UINT message, WPARAM wParam, LPARAM lPa
 			return TRUE;
 		}
 
+		case NPPM_INTERNAL_RESTOREMONOINSTANCE:
+		{
+			// When mono instance, bring this one to front
+			if (_pTrayIco != nullptr && _pTrayIco->isInTray())
+			{
+				// We are in tray, restore properly..
+				::SendMessage(hwnd, NPPM_INTERNAL_MINIMIZED_TRAY, 0, WM_LBUTTONUP);
+			}
+			else
+			{
+				// We were not in tray..
+				int sw = 0;
+
+				if (::IsZoomed(hwnd))
+					sw = SW_MAXIMIZE;
+				else if (::IsIconic(hwnd))
+					sw = SW_RESTORE;
+
+				if (sw != 0)
+					::ShowWindow(hwnd, sw);
+
+				::SetForegroundWindow(hwnd);
+			}
+			
+			return TRUE;
+		}
+
 		case WM_SYSCOMMAND:
 		{
 			const NppGUI & nppgui = (nppParam.getNppGUI());

PowerEditor/src/resource.h

@@ -644,6 +644,7 @@
 	#define NPPM_INTERNAL_CLEANSMARTHILITING            (NOTEPADPLUS_USER_INTERNAL + 68)
 	#define NPPM_INTERNAL_CLEANBRACEMATCH               (NOTEPADPLUS_USER_INTERNAL + 69)
 	#define NPPM_INTERNAL_WINDOWSSESSIONEXIT            (NOTEPADPLUS_USER_INTERNAL + 70)
+	#define NPPM_INTERNAL_RESTOREMONOINSTANCE           (NOTEPADPLUS_USER_INTERNAL + 71)
 
 // See Notepad_plus_msgs.h
 //#define NOTEPADPLUS_USER   (WM_USER + 1000)

PowerEditor/src/winmain.cpp

@@ -531,17 +531,8 @@ int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR pCmdLine, int)
 			// First of all, destroy static object NppParameters
 			nppParameters.destroyInstance();
 
-			int sw = 0;
-
-			if (::IsZoomed(hNotepad_plus))
-				sw = SW_MAXIMIZE;
-			else if (::IsIconic(hNotepad_plus))
-				sw = SW_RESTORE;
-
-			if (sw != 0)
-				::ShowWindow(hNotepad_plus, sw);
-
-			::SetForegroundWindow(hNotepad_plus);
+			// Restore the window, bring it to front, etc
+			::SendMessage(hNotepad_plus, NPPM_INTERNAL_RESTOREMONOINSTANCE, 0, 0);
 
 			if (params.size() > 0)	//if there are files to open, use the WM_COPYDATA system
 			{