Pcbnew, Fp Editor, pad_tool::PlacePad() avoid recreate from scratch a pad

when the previous is not used.
If a new pad is generated, when moving it by arrow creates a new pad for
each move by the current code.
This is not annoying unless the pad number is edited during move.
So, the pad number is now reinitialized only after the current pad is used,
not during the current move.
Fixes #16409
https://gitlab.com/kicad/code/kicad/-/issues/16409

pcbnew/tools/pad_tool.cpp

@@ -532,6 +532,12 @@ int PAD_TOOL::EnumeratePads( const TOOL_EVENT& aEvent )
 
 int PAD_TOOL::PlacePad( const TOOL_EVENT& aEvent )
 {
+    // When creating a new pad (in FP editor) we can use a new pad number
+    // or the last entered pad number
+    // neednewPadNumber = true to create a new pad number, false to use the last
+    // entered pad number
+    static bool neednewPadNumber;
+
     if( !m_isFootprintEditor )
         return 0;
 
@@ -542,6 +548,7 @@ int PAD_TOOL::PlacePad( const TOOL_EVENT& aEvent )
     {
         PAD_PLACER( PAD_TOOL* aPadTool )
         {
+            neednewPadNumber = true;    // Use a new pad number when creatin a pad by default
             m_padTool = aPadTool;
         }
 
@@ -578,9 +585,18 @@ int PAD_TOOL::PlacePad( const TOOL_EVENT& aEvent )
             if( pad->CanHaveNumber() )
             {
                 wxString padNumber = m_padTool->GetLastPadNumber();
-                padNumber = m_board->GetFirstFootprint()->GetNextPadNumber( padNumber );
+
+                // Use the last entered pad number when recreating a pad without using the
+                // previously created pad, and a new number when creating a really new pad
+                if( neednewPadNumber )
+                    padNumber = m_board->GetFirstFootprint()->GetNextPadNumber( padNumber );
+
                 pad->SetNumber( padNumber );
                 m_padTool->SetLastPadNumber( padNumber );
+
+                // If a pad is recreated and the previously created was not placed, use
+                // the last entered pad number
+                neednewPadNumber = false;
             }
 
             return std::unique_ptr<BOARD_ITEM>( pad );
@@ -589,6 +605,9 @@ int PAD_TOOL::PlacePad( const TOOL_EVENT& aEvent )
         bool PlaceItem( BOARD_ITEM *aItem, BOARD_COMMIT& aCommit ) override
         {
             PAD* pad = dynamic_cast<PAD*>( aItem );
+            // We are using this pad number.
+            // therefore use a new pad number for a newly created pad
+            neednewPadNumber = true;
 
             if( pad )
             {