Describe the bug
When some file is set as input of Paint Data and if we add more points to the plot and then click Reset to Input Data, the plot resets but the actual output doesn't, the widget outputs all file instances plus those added ones.

Additionally, when Clear is pressed the plot is empty and output is None and if then we click Reset to Input Data, the plot shows input instances but output is still None.

To Reproduce

1. Connect Iris file to the Paint Data widget
2. Add more points on the plot / Clear the plot
3. Click Reset to Input Data
4. Connect Paint Data to Data Table and see the number of output instances

Orange version:
3.25.dev

Expected behavior
The widget resets and outputs (only) the input data.