Start with the whole buffer selected in filter mode

src/main.cc

@@ -405,7 +405,7 @@ int run_filter(StringView keystr, memoryview<StringView> files)
         {
             try
             {
-                InputHandler input_handler{{ buffer, Selection{} }};
+                InputHandler input_handler{{ buffer, Selection{{0,0}, buffer.back_coord()} }};
 
                 for (auto& key : keys)
                     input_handler.handle_key(key);