What to pack for a Malaysia trip?

There are number of things which are necessary for this trip and things which you really don't need them. No need to increase your backpack weight with warm cloths as you are travelling to a tropical country. Just bring a sweatshirt because shopping malls and public transport are sometimes very cold because of air conditioners or you may need it while travelling to amazing highlands around Kuala lumpur.
Make sure to bring along your sunglasses, umbrella, slippers, light cloths, cap/hat, sunscreen. I strongly recommend you to buy the special body spray for mosquitoes to protect yourself from dengue and other insects if you feel yourself attractive for them. You can google for dengue to know more about it.
These are the things just came to my mind. If there is anything else to add, you can mention it in the comments.