Compatibility:  WIN 3.0+
Expects: AX    170aH
DX    GDI information index (see below)
                                                                  
Returns: AX    integer value of desired item
0000h = error
                                                                  
Info: This can be used to obtain information about the capabilities of
the Windows display device driver. Equivalent to GetDeviceCaps.

This calls the windows fn GetDeviceCaps, passing an hDC (handle
to a Device Context) of the display device.

DX is one of the index numbers that may be used in the Windows
GetDeviceCaps call.  For instance, DX=0004H obtains the
horizontal size of the display, in pixels and DX=0006H obtains
the vertical size.

These index values (and the often bit-encoded) return values can
be found by browsing the Windows.H - part of the SDK.

Note: It's not clear to me why this fn is included with the Clipboard
fns.

- -

INT 2fH 170aH: Obtain Device Capabilities