hello @TNTDAVID. thanks for your reply. I solved the problem by exploding the component and rebuilding it again.

@JQL, all of those steps were already taken by me. if you take a look at the attached pictures, you'll be able to see those "little squares", that you mentioned, placed right above the cabinet. I believe that I'm dealing with one more of many bugs found in SketchUp.

I don't know what really is doing him lose his "coolness" but this chat has more to do with an air conditioner machine .

@TIG, I did not misconstrue what you said. if I made you to understand so, l apologize.
I have another DC which has basically the same structure (with mother component and subcomponents) and it is working pretty fine. I can change its material thru the dropdown list that I put available on the component options screen. and I didn't need to do all those changes to make it work.

about the white color, what I wanted to say is that it is saved in the system as Color_000, both display and current name. I set the material behavior to the same Color_000, which was supposed to change the component color to white but it didn't happen, unsuccessfully. on the other hand, when I use the bucket tool to paint the component (not the faces), it works.

@TIG, is this your defintive comment? because it didn't work anyway. I opened Ruby Console, run both lines of code that you suggested and noticed that the white color name for both display and current's name are the same: Color_000. exactly the same name I used in the material behavior setting. it didn't change the color to white, which, according to you, it should work. the same happened to the Wood Floor material, which display and current's name are saved as Wood Floor and [Wood Floor], respectively.

material behavoir setting.

please, take a look at the attached picture and tell me what is missing.

the material "Wood_Floor" is available in Model. so, it was supposed to work.

but this material has been used in the model, as you can see in the picture. I'm trying to change the side finishing. top and bottom finishing already have this material applied. it was supposed to work, so.

yes, @Rich O Brien. it is a DC.

@JQL, as you suspected, the faces of the component were already painted. so I selected all the faces and set them to "Default" material, as you can see attached. then I could finally paint the component with one click using the bucket tool.

now there's a new problem. I tried to change the component material with the "Material behavior", it says that the selected material is not in model but, as you can see, it is!

thanks.