Flags specified for LPFNIG_ISIS_AREA, set with the IG_ISIS_area_dialog_CB_register function.
Values:
| IG_ISIS_AREA_INIT | Used when the preview window is created. |
| IG_ISIS_AREA_DONE | Used when the preview window is destroyed. |
| IG_ISIS_AREA_GET | Called during dialog initialization to request values from the callback describing the image that will be painted. |
| IG_ISIS_AREA_SET | Unused. |
| IG_ISIS_AREA_PAINT | The callback should scale and paint its image into the supplied destRect using the supplied clipping rectangle (clipRect) and device context (hDC). |