Add missing shadow from config button in game info dialog

Relates to #4349

src/fheroes2/agg/agg_image.cpp

@@ -366,6 +366,19 @@ namespace fheroes2
                     Sprite & out = _icnVsSprite[id][i];
                     out = GetICN( ICN::REQUESTS, 1 + i );
 
+                    // cut out top-left and bottom-right corners
+                    if ( !out.singleLayer() ) {
+                        const int cornerSize = 3;
+                        for ( int y = 0; y < cornerSize; ++y ) {
+                            for ( int x = 0; x < cornerSize; ++x ) {
+                                if ( x >= y ) {
+                                    SetTransformPixel( out, cornerSize - x, y, 1 );
+                                    SetTransformPixel( out, ( out.width() - 1 ) - cornerSize + x, ( out.height() - 1 ) - y, 1 );
+                                }
+                            }
+                        }
+                    }
+
                     // add 'config'
                     Blit( GetICN( ICN::BTNDCCFG, 4 + i ), 31 - i, 20, out, 10 - i, 4, 77, 16 );
                 }

src/fheroes2/dialog/dialog_gameinfo.cpp

@@ -27,6 +27,7 @@
 #include "game.h"
 #include "game_over.h"
 #include "icn.h"
+#include "image_tool.h"
 #include "localevent.h"
 #include "maps.h"
 #include "player_info.h"
@@ -113,6 +114,9 @@ void Dialog::GameInfo( void )
     fheroes2::Button buttonOk( pt.x + 178, pt.y + 426, ICN::REQUESTS, 1, 2 );
     fheroes2::Button buttonCfg( pt.x + 50, pt.y + 426, ICN::BTNCONFIG, 0, 1 );
 
+    const fheroes2::Sprite configBtnShadow = fheroes2::addShadow( fheroes2::AGG::GetICN( ICN::BTNCONFIG, 0 ), fheroes2::Point( -4, 4 ), 3 );
+    fheroes2::Blit( configBtnShadow, display, buttonCfg.area().x - 4, buttonCfg.area().y );
+
     buttonOk.draw();
     buttonCfg.draw();