Windows bitcoincash: Protocol Registration WRONG

Not sure when or where you guys set the **HKEY_CLASSES_ROOT\bitcoin-abc** registry value, but it should be **HKEY_CLASSES_ROOT\bitcoincash** instead. You should probably also change the **URL:Bitcoin** to **URL:BitcoinCash** or something for the default value of the key. As it is, the software thinks it should handle **bitcoin-abc:bitcoincash:MYADDRHERE**, but then completely fails to parse it once it receives it.
In the same vein, the protocol handler needs one change: standardized handling of spaces. Spaces are not usually allowed in URIs, and end up getting replaced with **plus signs** or **percent-twenties**, as we all know, but the program currently treats both of those as plain text. It's probably best to follow Uniform Resource standards when using Uniform Resource Identifiers and Locations. Otherwise, it's practically impossible to include a space in a value via an HTML Form object.
Also, there should be some clarification as to whether the **bitcoincash:** prefix should be listed once or twice. If it's part of the value, a full URI would, by standards, be **bitcoincash:bitcoincash:MYADDRHERE**, which the software does seem to handle, but it should either be mentioned as allowed or not preferred or something, or specifically ruled out in the specs by simply saying the protocol must be included in plain-text and QR code representations rather than implying the prefix is part of the address.

Start by locating the Windows registry setup for the bitcoin-abc protocol and the protocol-handler URI parsing entry point; no specific files or tests are named. Reproduce the reported bitcoin-abc: and bitcoincash: cases, including spaces encoded as plus signs or percent-twenty, then verify the registry names, prefixes, and decoding behavior against the intended URI rules.

Written by the indexing model from the issue text.