After some research I know now what you mean with
I-beam cursor which was an unknown term for me. Nobody in Austria names the mouse pointer looking like a big
I (upper case
i as displayed with Times New Roman) indicating that a text can be selected or the caret can be positioned now with the mouse an
I-beam cursor.
In uedit32.exe and in ueres.dll there are some mouse cursors as resources included, but not the
I-beam cursor. So this mouse cursor used in UltraEdit is most likely one of the system wide mouse cursors. According to Microsoft article
make the mouse easier to use, it is possible to change the color of the mouse pointers. I have not tested if changing the mouse pointer color system wide works for the
I-beam cursor in UltraEdit, too.
In general there will be always a problem with applying a color theme to an application which is completely different to the Windows color theme as there will be always some elements defined system wide which do not fit to the color theme of the application.
However, you and anybody else using now with UE v20.00 a dark color theme can sent nevertheless a feature request email to IDM support to make the color of the mouse pointers also customizable, or give the users the possibility to overload mouse cursors from another source (resource DLL).
I'm just wondering that the color of the text mouse pointer is raised now as a problem as the colors in document window area were always customizable and therefore it was always possible to use a dark theme for displaying the contents of text files.