I see what you mean!

Let me see if I can explain this so it's easy to understand.

When you make a picture for your gallery you obviously want it to be large so people can see the detail.  I frequently use the size  800 x 800 because I like symmetry.

You would render the image in Poser at a size of 800 x 800.  Then take it to your graphic program and do whatever work you want on it until the image is just right for you and ready to be uploaded to your gallery.

Save the file according to the method I have posted above.

Now you need a thumbnail image.

So create a new blank template of 200 x 200.

Go back to your big image that is ready for the gallery and copy it.

Go back to the 200 x 200 blank template and then paste the big image there as a new layer.

Move the image around until you see something in the 200 x 200 space that you like. What you see will be the what is on your final thumbnail image.  Everything off the edge of that 200 x 200 space will be deleted once you save the image as a .jpg. All you will be left with is a portion of your image in a 200 x 200 file.

The reason I do it that way is that my thumbnails are always 200 x 200.

When you upload your image in the gallery, you will upload the big 800 x 800 image, AND the 200 x 200 thumbnail image.

Renderosity will create a link between the thumbnail and the big image so when you are in the gallery it will show the big image.  It's not the thumbnail that is increasing in size or "opening up" to show a larger image.  The thumbnail will always be just 200 x 200 after you save it unless you go and resize it to other dimensions, but the picture part of it will always be the same once you have saved it.

When you post in the forums, that's a different story.  In the forums the images are resized to fit into a preset limit.  So if you upload an image in the forum that is say 800 x 800, it will be reduced to a smaller size so that it won't stretch out the forum and result in left-right scrolling. In these cases when you click the image the image will show up as their full size in the new window.  However if your image that you are posting in the forum is less than the preset size for the forums (not sure what that is), then the image will not be reduced in size and even when you click it will show as the same size in the new window.  An example of that is the 200 x 200 image you posted above of your parameter dials.

Try it for yourself and see.  You know what happens with a 200 x 200 image because you just posted one above.  Now go and create one that is 800 x 800 and post it here. The image will be smaller in the post, but once you click the image it will show up at 800 x 800.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi