The short answer is: Don't share your wallet between devices. Use different wallets instead and move Bitcoins between them. Just like you would do with traditional wallets for daily spending vs. bank accounts for savings.
That would be workable, if the wallets did not have problems which prevent you from sending your funds. When Bitcoin Wallet will not allow me to send, I have to import my keys into my desktop.
It's rather absurd in general. The data is in the blockchain. Why do I have to have access to a particular device in order to use my keys? That is a usability defect which, in practice, is causing people to lose access to their funds.
