ShowModal has a bug in Linux
lazarus / 32-Linux

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Jesse Jin · 2025-04-26 02:29

1. Form1.Button1Click -> Form2.ShowModal
2. Don't close Form2, click Form1 -> click Form2
3. Form1.OnDeactivate will work

In windows，it's wright!

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TRon · 2025-04-26 03:06

Hi and welcome Jesse Jin,

Sorry but I have no idea what you are trying to tell with your
message. I do not won or use windows so I do not know what behaviour
Windows OS displays.

Do you mean that on Linux the OnDeactivate message should be displayed
? Or do you mean the behavipur should be the other way around?

Besides that, behaviour might depend on used widgetset, display-
server, windows manager etc.

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zeljko · 2025-04-26 12:16

I can reproduce it here but only with gtk3 ws (KDE Plasma, linux mint
22.1).

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Jesse Jin · 2025-04-28 00:52

Quote from: TRon on April 26, 2025, 05:06:48 amHi and welcome Jesse
Jin,

Sorry but I have no idea what you are trying to tell with your
message. I do not won or use windows so I do not know what behaviour
Windows OS displays.

Do you mean that on Linux the OnDeactivate message should be displayed
? Or do you mean the behavipur should be the other way around?

Besides that, behaviour might depend on used widgetset, display-
server, windows manager etc.

When Form2.ShowModal is called, Form1 should never be able to move,
maximize, minimize, or trigger the OnDeactivate event.

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TRon · 2025-04-28 01:02

Quote from: Jesse Jin on April 28, 2025, 02:52:38 amWhen
Form2.ShowModal is called, Form1 should never be able to move,
maximize, minimize, or trigger the OnDeactivate event.
fwiw on my mate, gtk2 setup it behaves exactly as described. It is not
possible for me to do anything with form1 (besides make it visible by
moving the second form). Form1 does not respond to anything.

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Jesse Jin · 2025-04-28 06:43

Quote from: TRon on April 28, 2025, 03:02:45 amQuote from: Jesse Jin
on April 28, 2025, 02:52:38 amWhen Form2.ShowModal is called, Form1
should never be able to move, maximize, minimize, or trigger the
OnDeactivate event.
fwiw on my mate, gtk2 setup it behaves exactly as described. It is not
possible for me to do anything with form1 (besides make it visible by
moving the second form). Form1 does not respond to anything.
I use Debian 12, and DE is xfce. But mate or kde or gnome or cinnamon
is same to xfce.  :'(

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TRon · 2025-04-28 09:34

@Jesse Jin:
Are you by any chance running xfce using wayland display server ?

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Jesse Jin · 2025-04-30 08:01

I gave up!

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TRon · 2025-04-30 14:14

Well, there is nothing much to go one there Jesse Lin.

From the attached demo we have to conclude you are running Lazarus 3.6
(which kind of is outdated in terms of GUI related improvements) on a
OS we know nothing about other than the basic knowledge shared (debian
12/xfce)

Are we perhaps suppose to install random bookworm/xfce setups with
Lazarus 3.6 in order to try reproduce the problem ? Do we need a
specific cpu for that as well ? (nobody reading this thread knows)

Since it is basic functionality for sure there must have been more
people having reported the issue by now so, it is either a unusual
combination in/of the setup or an issue that got fixed. And yes, it
could even be a unique new issue.

Giving up implies having tried a couple of things but what exactly was
not mentioned.

edit: typo.