Drawing bug with VCL Styles

[luebbe 26]

Hi Folks,

 

I have a strange bug when a VCL styled application is maximized in a dual monitor configuration.

 

Steps to reproduce:

1. Set your windows task bar position to "top"

2. Create a minimal application and activate a VCL style (add a main menu if you like)

3. Run the application and:

   * maximize it on the primary monitor (fine)

   * maximize it on the secondary monitor (The top part of the application, probably the height of the windows task bar, becomes transparent)

 

 

left: maximized on primary monitor

right: maximized on secondary monitor

 

Additional Info:

* My two monitors have different resolutions and they have a vertical offset

* This bug doesn't seem to affect many people (no customer has reported it so far ;-))

* This is not a new bug. I've seen for years (three to four) it in several Delphi versions, but I can't put a date on it

 

Today I tried to find out if it is a problem with our main form's settings, but since it also happens with a minimal application, it probably isn't.

Has anybody encountered this as well?

Does anyone know how to fix it?

Do I have to wait for Emba to fix it?

 

Cheers & thanks

Lübbe

 

[Lars Fosdal 1792]

Do the two screens have different DPI?

What kind of HighDPI settings do you have in the manifest?

[luebbe 26]

I didn't touch anything knowingly in the manifest. Just dropped a menu on the form and activated a VCL style.

The minimal app has "per monitor v2"

Our standard app has "none"

So I guess it doesn't have anything to do with dpi awareness?

Edited July 1, 2021 by luebbe

[Lars Fosdal 1792]

Can you zip the project and attach the minimal app source here so that I can try your exact experiment on my two screen solutiuon?

I have two 4k screens, but of different size, and the smaller has a different scaling.

 

[luebbe 26]

Good morning Lars,

 

Thank you. Here it is.

Maximized.zip

[Lars Fosdal 1792]

I cannot replicate your problem on first try.
Menu and title bar looks ok maximized on both screens.

The size of the window adjusts according to DPI as I drag it from one screen to the other.

[Lars Fosdal 1792]

Also tried resizing the size of one monitor and aligning it to the top, as well as to the bottom.

No unexpected size effects.

 

Are you sure you are not running some Windows video driver software that manages windows?

 

[dwrbudr 8]

I can reproduce the issue. The main thing here is that the monitors should not be aligned.

The bug is already reported, but nobody seems to care:

 

https://quality.embarcadero.com/browse/RSP-27207

 

 

Edited July 2, 2021 by dwrbudr

[luebbe 26]

I was half fearing @lars' answer :)
Thanks to @dwrbudr for confirming it.

 

This is my monitor setup with (1) being the laptop monitor as secondary screen and (2) the desktop monitor as primary screen.

[Lars Fosdal 1792]

I didn't try that offset config. I always aligned the top or the bottom edges?

[Lars Fosdal 1792]

Ok, I tried with the vertical offsets as well.  No change. Maximized perfectly - even when spanning both displays.

I suspect driver antics?

 

What are the resolutions and scaling of monitor 1 and 2 ?

[luebbe 26]

Sorry for the late reply. It was a very busy week.

 

Monitor 1: 1920x1080 (??" Laptop screen)

Monitor 2: 2560x1440 (27")

Both set to 100% font scaling

 

It also happens on my desktop PC at work, which has two 24" monitors with different resolutions

Monitor 1: 2560x1440 (24")

Monitor 2: 1920x1080 (24")

Both set to 100% font scaling

They have a slight vertical offset IIRC (working from home, desktop is in the office)

 

May be driver antics, but our IT department keeps everything as up-to-date as possible.

 

I'll compile it with the community edition on my home PC and try what happens there.

Edited July 13, 2021 by luebbe

[luebbe 26]

Yes, immediately reproducible on my home PC

 

Screen layout:

 

Monitor 1: 1920x1080 (24")

Monitor 2: 2560x1440 (27")

 

When both monitors align at the top, everything is fine.

 

This is also sufficient.

 

You have to toggle the app between normal and maximized mode after you change the screen alignment. If you leave the app maximized while changing the screen alignment, everything will stay ok.

Edited July 13, 2021 by luebbe

[Lars Fosdal 1792]

Still unable to reproduce (10.4.2).

[luebbe 26]

Lucky you 😉

 

10.4.2 + all patches (work laptop)

10.4.1 + all patches (work desktop)

10.3.x community edition (home)

Edited July 13, 2021 by luebbe