Update to Avalonia 12.0.0 - #476

This construct is experimental. Same as Observable, but fires once immediately after subscribing. This warning can be disabled using '--nowarn:57' or '#nowarn "57"'.

This construct is experimental. Same as Observable, but fires once immediately after subscribing. This warning can be disabled using '--nowarn:57' or '#nowarn "57"'.

This construct is experimental. Same as Observable, but fires once immediately after subscribing. This warning can be disabled using '--nowarn:57' or '#nowarn "57"'.

This construct is experimental. Same as Observable, but fires once immediately after subscribing. This warning can be disabled using '--nowarn:57' or '#nowarn "57"'.

This construct is experimental. Same as Observable, but fires once immediately after subscribing. This warning can be disabled using '--nowarn:57' or '#nowarn "57"'.

This construct is experimental. Same as Observable, but fires once immediately after subscribing. This warning can be disabled using '--nowarn:57' or '#nowarn "57"'.

The recursive object reference 'this' is unused. The presence of a recursive object reference adds runtime initialization checks to members in this and derived types. Consider removing this recursive object reference.

This attribute cannot be applied to struct. Valid targets are: class

This attribute cannot be applied to struct. Valid targets are: class