You should only be able to put an iten into the toolbar if the item was placed in your melee/gun slot or in the vest/shirt/pants, since its quite difficult to take an item from your backpack without looking at it. Other Ideia is to change the shape of clothes inventory depending on their real pocket position, it would be really interesting to see it in all clothes, but on the backpacks would be the best, making it much more close to reallity. An example of the second mechanic made in photoshop: