After setting limited width size,strings which is too long get truncated in the dropdown of wxcombobox.
self.namelist = wx.ComboBox(self, -1, "", size=(270,-1))
Is there any way to make the combobox dropdown scrolls horizontally.So that we can see long strings.?
No, but you can use wx.combo.ComboCtrl instead which lets you implement the drop-down window yourself, and then you can make it do whatever you want.  It's not a perfect emulation of the wx.ComboBox, and fairly complex compared to the wx.ComboBox, so it may not be worth it to you for just adding horizontal scrolling.  You can see examples in the wxPython demo.
Can we set horizontal scrollbar for wxcombobox?