In creative mode in Minecraft 1.7.4, if you have a sword in your hotbar, and you move it to a different spot on your hotbar using the number keys, when you hold that sword in creative, you can still break blocks.
FOR EXAMPLE:
I have a golden sword in creative in the first slot of my hotbar. I open my creative inventory, hover my mouse pointer over the golden sword, and push "2" on my keyboard. I exit my inventory, and I switch to slot 2 in my hotbar, which my golden sword is now in. I can now break blocks, even though I am holding a sword.