[Lazarus] Application GUI does not appear

Michael Van Canneyt michael at freepascal.org
Mon Dec 26 16:09:01 CET 2022

On Mon, 26 Dec 2022, Koenraad Lelong via lazarus wrote:

> Hi,
> It's been a while since I did some development with Lazarus.
> Now I wanted to update an application I wrote some years ago. At that time 
> the application was written and compiled on and for Linux.
> Now I want that application to run on Windows 11 64bit.
> I installed the latest Lazarus (2.2.4 64bit) on a Windows 11 machine and 
> copied my sources to that machine.
> After some struggling with a missing library (libmysql.dll) I managed to run 
> the original application. But I could not see the GUI.
> Then I discovered I could not modify the forms, I simply can't see them. 
> Pressing F12 does nothing but greying out the caption of the editor.
> I can see the form of the datamodule though.
> I used the "Check LFM-file in editor"-tool and that checks OK for the 
> GUI-forms.
> I added an msgDialog in the on-show routine of the main form and that does 
> show. But when I click that away, nothing shows anymore, just the icon in the 
> task-bar.
> I created a minimal application and that does work fine.
> Any Ideas what is happening ?

It could be that the support for High-DPI is messing with your forms. 
If the messagedialog works, it shows that the form is loaded and being shown.
Probably it has size zero.

So maybe check the form sizes in the lfm file, also check whether a
LCLVersion is being streamed. If so, maybe change its value to


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