Can we set background color for a button in runtime?

Hi, In my application, I have one action button called "Upload File". When I click on it, it allows me to select file from my system. Now, after adding a file I want to change the back-ground color or button color to green. As an indication for we already uplaoded a file. Can I approch this?? Can any one please help me. Or else give me suggestions to identify that the file is already uplaoded.....     Thanks & Regards, Venkat.
1 answers

Have an attribute on the entity that indicates if a file has been uploaded.  System.FileDocument has a built in attribute called HasContents, which indicates this.  On your page in the Modeler, have 2 buttons:  the first would have a color indicating a file has not been uploaded and the second has a color indicating a file has been uploaded.  Make the first button visible when HasContents - false, make the second button visible when HasContents - true.