Its only there if you have a watch only wallet.
On your cold wallet click:
Wallet -> Master public key (MPK) and copy the string / scan the QR code
On your hot wallet click:
File -> New/Restore -> cold_test.wallet (or whatever you want to call your file) -> save -> "create watching-only version of an existing wallet" -> Next -> paste the MPK -> Next -> Auto connect/Select server manually -> Next -> done.
Now your send has the needed button.