Color Highlight of ListBox or ComboBox Entries

[Gintaras]

change the background color of the combobox regardless of whether there was any items

Can't answer.

is there a version of DT_SetBackgroundColor that works on child object (edit, richedit, listbox, button, etc)

Probably exist functions in the forum for some control types, don't remember. Usually need to either disable control theme (then looks not good) or draw entire control (difficult).