There are two fairly simple ways to eliminate the warning.
Remove the .gtkrc file from your home directory on the host.
Note: This causes all applications based on GTK+ to use the default theme. Any settings stored in ~/.gtkrc (or in files that it includes) may revert to defaults. If you regularly use custom styles in your other applications, you may prefer the second solution.
Contact Red Hat for a 32-bit Bluecurve theme engine compatible with GTK+ version 1, or locate the Bluecurve theme on the Web. (Bluecurve is found in the redhat-artwork RPM.) Installing a compatible Bluecurve theme allows VMware Workstation or the VMware Console to use the default Bluecurve theme specified by the .gtkrc file.
If, in your case, the warning message refers to a theme other than Bluecurve, you need to locate and install a 32-bit engine for that theme, compatible with GTK+ version 1.----