Adjust selection bounds for CTabRenderring

[ShahzaibIbrahim]

Selected tabs highlight look slightly off and more noticeable when zoom is not 100%. These adjusted value shows no gaps from top and better aligned highlights for tabs (Theme is enabled)

Results:

[github-actions]

Test Results

 3 018 files  +142   3 018 suites  +142   2h 22m 8s ⏱️ + 27m 45s
 8 248 tests ±  0   7 999 ✅  -   1  248 💤 ± 0  1 ❌ +1 
23 664 runs  +702  22 872 ✅ +636  791 💤 +65  1 ❌ +1 

For more details on these failures, see this check.

Results for commit 046398a. ± Comparison against base commit db4295a.

♻️ This comment has been updated with latest results.

[HeikoKlare]

With this change, the highlight line looks very thin (on 100%):

This is how it used to look:

[ShahzaibIbrahim]

@HeikoKlare I found the problem. Here were drawing the tab from (0,0) pixel but still using initial item location (1,1) and hence the gap was visible. I also updated the height to 3 when we draw from (0,0) so we have enough height for the selection marker.

The code that caused the gap:
https://github.com/vi-eclipse/eclipse.platform.ui/blob/8be04038fd7a1dd5cf4f7972e7813d0925181315/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/CTabRendering.java#L572C2-L577

[HeikoKlare]

The appearance is in my opinion much better than before. I have some questions/remarks on the current propose.
And the appearance with round tabs now became worse (than it already was before):

We may probably do something similar than in SWT to draw a proper shape. The current adjustments by 1 point based on cornerSize do not look sufficient.

[ShahzaibIbrahim]

The appearance is in my opinion much better than before. I have some questions/remarks on the current propose. And the appearance with round tabs now became worse (than it already was before):

We may probably do something similar than in SWT to draw a proper shape. The current adjustments by 1 point based on cornerSize do not look sufficient.

While I agree the rounded tabs should be adapted. But I wouldn't say it looks "worse" than master. Here's the SS comparing this PR and master state.

I would suggest that we fix the shape in another PR. This PR fixes the gap that we had from the top.

[amartya4256]

I pulled the branch and ran it on 250%. This is how it looks for me:

I can see a small gap in the left and at the top. Is it supposed to look like this?

[HeikoKlare]

I can see a small gap in the left and at the top. Is it supposed to look like this?

No, it should be fully aligned at the top, left and right without any gaps at every zoom.

[ShahzaibIbrahim]

I pulled the branch and ran it on 250%. This is how it looks for me:

I can see a small gap in the left and at the top. Is it supposed to look like this?

Are you sure you checked out master-517 from platform.ui? We also have master-517 for SWT. I checked again and there is no gap for the highlight.

[HeikoKlare]

@amartya4256 can you please retest this? Unfortunately, I have currently monitor available that I can set to 250%. Everything up to 225% looks fine to me.

[HeikoKlare]

I would suggest that we fix the shape in another PR. This PR fixes the gap that we had from the top.

@ShahzaibIbrahim But maybe that would require another readaptation of the calculations. Shouldn't we just fix it right away? Then it would also make more sense to take into account the outlineBoundsForOutline as those are used by the calculations for the (potentially rounded) borders.

[ShahzaibIbrahim]

I would suggest that we fix the shape in another PR. This PR fixes the gap that we had from the top.

@ShahzaibIbrahim But maybe that would require another readaptation of the calculations. Shouldn't we just fix it right away? Then it would also make more sense to take into account the outlineBoundsForOutline as those are used by the calculations for the (potentially rounded) borders.

I have added a commit to put highlight on rounded tabs. Although it looks big jagged as original one (non-selected rounded tabs) also bit jagged. I have reused the shape.

Here's the comparison of the selected and unselected tabs:

[eclipse-platform-bot]

This pull request changes some projects for the first time in this development cycle.
Therefore the following files need a version increment:

bundles/org.eclipse.e4.ui.workbench.renderers.swt/META-INF/MANIFEST.MF

Warning

🚧 This PR cannot be modified by maintainers because edits are disabled or it is created from an organization repository. To obtain the required changes apply the git patch manually as an additional commit.

Git patch

From d1e7f2d1fabc7ac074af0a8ef8219a8b09b14361 Mon Sep 17 00:00:00 2001
From: Eclipse Platform Bot <platform-bot@eclipse.org>
Date: Mon, 15 Dec 2025 12:58:37 +0000
Subject: [PATCH] Version bump(s) for 4.39 stream


diff --git a/bundles/org.eclipse.e4.ui.workbench.renderers.swt/META-INF/MANIFEST.MF b/bundles/org.eclipse.e4.ui.workbench.renderers.swt/META-INF/MANIFEST.MF
index 249542c521..ca4f9ad426 100644
--- a/bundles/org.eclipse.e4.ui.workbench.renderers.swt/META-INF/MANIFEST.MF
+++ b/bundles/org.eclipse.e4.ui.workbench.renderers.swt/META-INF/MANIFEST.MF
@@ -1,7 +1,7 @@
 Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-SymbolicName: org.eclipse.e4.ui.workbench.renderers.swt;singleton:=true
-Bundle-Version: 0.16.1000.qualifier
+Bundle-Version: 0.16.1100.qualifier
 Bundle-Name: %pluginName
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin
-- 
2.52.0

Further information are available in Common Build Issues - Missing version increments.

[ShahzaibIbrahim]

After latest adaptation, there is no more "Bleeding" on the very left and right. The selection highlight looks fine to me in different zoom levels. Also addressed the comments from you @HeikoKlare. Let me know if I miss something.

[HeikoKlare]

We seem to be coming closer. The code became much simpler and many scenarios now look good.
But with rounded corner, the highlight is still far too large. At 150%, it looks like this (compare to the "correct" hight for the non-focused "problem" view below):

When reducing the hight by 1, I see the rendering artifacts mentioned before again.
The screenshots in the previous post seem to be taken with some custom auto-scaling settings. The tab icons are not scaled according to the text, so probably monitor-specific scaling is disabled or some custom auto-scale configuration is active.

[ShahzaibIbrahim]

We seem to be coming closer. The code became much simpler and many scenarios now look good. But with rounded corner, the highlight is still far too large. At 150%, it looks like this (compare to the "correct" hight for the non-focused "problem" view below):

I reduced the height by 1 and fixed the bleeding and this is how it looks now. For me its too small now. But if it feels okay to you I can push the changes.

[ShahzaibIbrahim]

As discussed earlier, the highlight height for the curved and non-curved tab folders should be same. I have adjusted the height now. This is the final result.

[HeikoKlare]

I looks almost fine now. But the lines still do not have the same height, such that the highlight bar with rounded corners appear a bit too thick and prominent. These are the heights I get:

• 100%: round corners 3px, square corners 2px
• 175%: round corners 5px, square corners 4px

Here is the comparison of the highlight at 100% with round corners before (top) and after (bottom) this change:

The overall appearance is definitely much better, but the line is thicker now.

Removing my request for changes as the major concerns are addressed and basically only the line thickness in scenario is missing. Thus I cannot approve yet, but since I will be on vacation soon I do not want to have my request for change block progress here.

[ShahzaibIbrahim]

I looks almost fine now. But the lines still do not have the same height, such that the highlight bar with rounded corners appear a bit too thick and prominent. These are the heights I get:

• 100%: round corners 3px, square corners 2px
• 175%: round corners 5px, square corners 4px

The final fix meant we have consistent size for highlighting in CTabFolders for both square and rounded tabs. See.