Fix loosing all open files after restarting as Admin to save a file

While saving a file needs the admin privilege, and if "Always In Multi-Instance Mode" option is activated, the current Notepad++ instance will be closed and a new instance with admin privilege contains no file is launched - it makes user confused because there are nothing to be edited and saved.

This commit fixes the issue by keeping the 1st instance opened, and launching the 2nd instance (with admin privilege) which contains the file in question - so user can modify it and save it.

The new behaviour (of this commit) not only fixes the issue, but also makes more sense, since it's "Always In Multi-Instance Mode". Note that the same behaviour happens if the session & periodical backup feature is disabled.

Fix #14694, close #14701

PowerEditor/src/NppIO.cpp

@@ -655,9 +655,12 @@ bool Notepad_plus::doSave(BufferID id, const TCHAR * filename, bool isCopy)
 		else
 		{
 			// try to open Notepad++ in admin mode
-			bool isSnapshotMode = NppParameters::getInstance().getNppGUI().isSnapshotMode();
-			if (isSnapshotMode) // if both rememberSession && backup mode are enabled
-			{                   // Open the 2nd Notepad++ instance in Admin mode, then close the 1st instance.
+			NppGUI& nppGui = NppParameters::getInstance().getNppGUI();
+			bool isSnapshotMode = nppGui.isSnapshotMode();
+			bool isAlwaysInMultiInstMode = nppGui._multiInstSetting == multiInst;
+			if (isSnapshotMode && !isAlwaysInMultiInstMode) // if both rememberSession && backup mode are enabled and "Always In Multi-Instance Mode" option not activated:
+			{                                               // Open the 2nd Notepad++ instance in Admin mode, then close the 1st instance.
+
 				int openInAdminModeRes = _nativeLangSpeaker.messageBox("OpenInAdminMode",
 				_pPublicInterface->getHSelf(),
 				TEXT("This file cannot be saved and it may be protected.\rDo you want to launch Notepad++ in Administrator mode?"),
@@ -691,8 +694,9 @@ bool Notepad_plus::doSave(BufferID id, const TCHAR * filename, bool isCopy)
 
 				}
 			}
-			else // rememberSession && backup mode are not both enabled
-			{    // open only the file to save in Notepad++ of Administrator mode by keeping the current instance.
+			else // rememberSession && backup mode are not both enabled, or "Always In Multi-Instance Mode" option is ON:
+			{    // Open only the file to save in Notepad++ of Administrator mode by keeping the current instance.
+
 				int openInAdminModeRes = _nativeLangSpeaker.messageBox("OpenInAdminModeWithoutCloseCurrent",
 				_pPublicInterface->getHSelf(),
 				TEXT("The file cannot be saved and it may be protected.\rDo you want to launch Notepad++ in Administrator mode?"),