Make new GTK4 Dialog dynamic loaded for pre GTK 4.10

[laeubi]

This is a draft to make the GTK4.10 dialog compile with older GTK versions

FYI @ptziegler @akurtakov

this is not complete but in case someone wants to pick it up I wanted to share my progress here, with this changes it actually compiles again now.

[github-actions]

Test Results

   486 files  ±0     486 suites  ±0   7m 53s ⏱️ +37s
 4 159 tests ±0   4 151 ✅ ±0   8 💤 ±0  0 ❌ ±0 
16 390 runs  ±0  16 298 ✅ ±0  92 💤 ±0  0 ❌ ±0 

Results for commit 49a1124. ± Comparison against base commit 5dd0c28.

♻️ This comment has been updated with latest results.

[akurtakov]

I'm giving it +1 as it will allow compiling on 4.8 (as debian stable has) although runtime requirement will be 4.10+. Having newer than that build requirement is not feasible as it will introduce even newer glibc and etc. .

[akurtakov]

Let's merge this one to allow compiling on debian image. We may need to bump

eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Display.java

Line 526 in e329edc

static final int GTK4_MINOR = 0;

to 4.10 which would mean that build machine wouldn't be able to smoke test things but as long as ubuntu-latest can - this is fine IMO. Also I believe that by the time gtk 4 is ready to be default 4.10 would be old enough (4.16 being the latest now). With the above said - if you agree do the change now but considering there is no easy way to even try it now, this change can be done later if/when people start finding it a problem.

[ptziegler]

Apologies for the late response. Generally, I agree with @akurtakov. I don't think the current GTK4 port is anywhere near a productive state and by the time it becomes stable, the bottom line of 4.10 will already be quite old.

This doesn't mean that we should always use the latest API, but at least for something that affects the UI like the dialogs, I believe that it is less of a headache to migrate it now, before it becomes widely used.

And when GTK4 becomes the default backend, I doubt that SWT will immediately drop GTK3, leaving it as an usable alternative for older platforms, at least for a few more releases.