Ability to add in custom image vanishes when Effect Maker is too shallow

Issue found:

• When you make the Effect Maker width as shallow as it can be, the small plus icon on Threshold mask is cut off. This may make the user not to find a way to add a custom image, unless the view is widened. This applies to Threshold Mask, Opacity Mask and Displace, MultiEffect, Fog, Lava, Clouds, Rain, Normal Mapping, Color LUT effects.

OK	Plus icon gone

• Snapshot: 43
• OS: Mac OS/ M1

How to reproduce

1. Create a project
2. Open Effect Maker
3. Create a Threshold mask or Opacity Mask or Displace effect (or any of the mentioned above)
4. Make the effect maker wider or more shallow. In the shallow end you see that the icon button will vanish from the view.

How it is expected to work

• The combobox should give a way for keeping the plus icon button in view