PixelPaint: Hold shift to increase move tool speed with the arrow keys

Holding shift while using the move tool with the arrow keys now moves
the selected layer in 10 pixel increments.

Userland/Applications/PixelPaint/Tools/MoveTool.cpp

@@ -141,7 +141,7 @@ bool MoveTool::on_keydown(GUI::KeyEvent& event)
     if (m_scaling)
         return true;
 
-    if (event.modifiers() != 0)
+    if (!(event.modifiers() == Mod_None || event.modifiers() == Mod_Shift))
         return false;
 
     auto* layer = m_editor->active_layer();
@@ -149,19 +149,19 @@ bool MoveTool::on_keydown(GUI::KeyEvent& event)
         return false;
 
     auto new_location = layer->location();
-
+    auto speed = event.shift() ? 10 : 1;
     switch (event.key()) {
     case Key_Up:
-        new_location.translate_by(0, -1);
+        new_location.translate_by(0, -speed);
         break;
     case Key_Down:
-        new_location.translate_by(0, 1);
+        new_location.translate_by(0, speed);
         break;
     case Key_Left:
-        new_location.translate_by(-1, 0);
+        new_location.translate_by(-speed, 0);
         break;
     case Key_Right:
-        new_location.translate_by(1, 0);
+        new_location.translate_by(speed, 0);
         break;
     default:
         return false;