Text input area flicker

I just started to use PSPad and the first thing that caught my eye, flicker in the text input area with a ruler and line numbers.

This effect is observed in versions 4.5.8 and 4.5.9 (2513) while text entering or just cursor movement. This is not depended of state Show/Hide Syntax highlighting. My OS is Windows 7.

Version 4.5.4 (2356) has no flicker.

Thank you for this product!

There is a new version of the editor component from the 4.5.6 version.
I must investigate editor component code and find a source of flicking.