When you click on the ComboBox, this causes it to be selected in the window. Is there a way to accomplish the javascript equivalent of blur ()
Not directly. However, you can try focusing on the root parent combobox or other element.
comboBox1.TopLevelControl.Focus();
or
someControl.Focus();
I had a similar problem and managed to fix it by disabling and re-enabling dropdowns.
comboBox1.Enabled = false; comboBox1.Enabled = true;