Accept lphc == NULL in listboxes

[Uwe Bonnes]

Changelog:
	controls/listbox.c: LISTBOX_HandleLButtonDownCombo/
	                    ComboLBWndProc_common
        Accept lphc == NULL in more places

This makes the properities list boxes in Xilinx Webpack work. As there are
other places where lphc == NULL is handled, it shouldn't be the wrong way.
The application was somehow unwilling to get debugged. Running the suite
from the commandline, it entered the debugger and looped endless. Running it
with winedbg, the loader hanged. Only with some application ("tkstartwdog
-C", also know as a problem causer in other EDA applications) of the
toolchain as a separate process and starting the target process ("_pn.exe -C
WebPACK4.2 -U MTOC.chm") in the debugger showed up the problem. Running the
target process in a normal wine process made the application catch the
exeption, show up a messagebox about that and crash in another place.

Bye
-- 
Uwe Bonnes                bon at elektron.ikp.physik.tu-darmstadt.de

Free Software: If you contribute nothing, expect nothing
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