Restore possibility to use Ctrl+Alt to copy selection and snap-to-grid at the same time (fix #3497)

If we don't activate Brush Size mouse wheel action when using Ctrl+Alt
key modifiers in a selection-like tool we can use Ctrl+Alt to make
copies of the selected region and snap-to-grid at the same time.

src/app/ui/editor/standby_state.cpp

@@ -497,6 +497,14 @@ bool StandbyState::onKeyDown(Editor* editor, KeyMessage* msg)
   Keys keys = KeyboardShortcuts::instance()
     ->getDragActionsFromKeyMessage(KeyContext::MouseWheel, msg);
   if (!keys.empty()) {
+    // Don't enter DraggingValueState to change brush size if we are
+    // in a selection-like tool
+    if (keys.size() == 1 &&
+        keys[0]->wheelAction() == WheelAction::BrushSize &&
+        editor->getCurrentEditorInk()->isSelection()) {
+      return false;
+    }
+
     EditorStatePtr newState(new DraggingValueState(editor, keys));
     editor->setState(newState);
     return true;