Anyone running Windows 10 Insider Preview 1773x or newer?

Anyone running Windows 10 Insider Preview 1773x or newer? I have a strange problem with Delphi applications and even the Delphi IDE: When editing the content of a TComboBox (default Style = csDropDown), the Backspace key (VK_BACK) deletes two characters instead of only one character!

Not only my applications are affected, even the Delphi IDE has the same behaviour:
Ctrl+F in the code editor show the "Search" panel at the bottom of the editor. The Backspace key deletes two characters. "Find in files" (Ctrl+Shift+F), "Replace Text" (Ctrl*R), Run->Parameters,... almost any TComboBox-based control deletes two characters on one Backspace keystroke. Even 3rd-party experts like GExperts' Grep search misbehaves like this.

But when using a TComboBoxEx, the Backspace key works normal.
I'm not sure if this is bug in Windows 10, or a bug in the VCL which shows only in the latest Windows 10 builds.