[Lazarus] IDE rebuild fails on raspi4

[Werner Pamler]

Am 07.02.2020 um 11:16 schrieb Tom Lisjac via lazarus:
> Trying to get Lazarus working on the raspberry pi 4 with the latest 
> Raspbian (Debian 10.2). Installed 2.0.0+dfsg-2 with synaptic from the 
> Raspbian repos, but haven't been able to install components and 
> rebuild the IDE, due to:
>
>   VirtualTrees.pas(70,3) Fatal: Cannot find OleUtils used by VirtualTrees.
>
> Got past a similar issue with fpdebug buy compiling it manually, but 
> the VirtualTrees source shows OleUtils inside a Windows ifdef which 
> isn't going to resolve on the pi:
>
> unit VirtualTrees;
> {$ifdef Windows}
>   ...
>   OleUtils,

I checked several versions of the Lazarus port on Luiz's github 
((https://github.com/blikblum/VirtualTreeView-Lazarus - the version 
included in Lazarus is based on v5)), and they all have OleUtils outside 
the Windows ifdef, the code is:

uses
   {$ifdef Windows}
   Windows,
   ActiveX,
   CommCtrl,
   {$else}
   laz.FakeActiveX,
   {$endif}
   OleUtils,
   ....

In fact, OleUtils is a unit which provides some Windows-functionality 
for other widgetsets. However, it does not belong the VirtualTreeViews - 
it is contained in the lclextensions package which you must compile 
first, before touching VirtualTreeViews. Maybe it is sufficient to 
simply do a clean rebuild of the IDE.