Takes a screenshot.
When the request is done, callback will be called. You can then call [[email protected]_screenshot_finish] to get the
results.
| this |
a [class@Portal] |
| parent |
parent window information |
| flags |
options for this call |
| cancellable |
optional [[email protected]] |
| callback |
a callback to call when the request is done |
| data |
data to pass to |