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Bug #14302

closed
SB RM

[Wt 4.12.2] Regression in WHBoxLayout::setResizable and WTreeView triggers endless width/resize loop

Bug #14302: [Wt 4.12.2] Regression in WHBoxLayout::setResizable and WTreeView triggers endless width/resize loop

Added by Stefan Bn 7 months ago. Updated 7 months ago.

Status:
Closed
Priority:
High
Assignee:
Romain Mardulyn
Target version:
4.12.3
Start date:
02/04/2026
Due date:
% Done:

0%

Estimated time:

Description

Hello Wt-Team,

I do experience serious issues in the latest version Wt 4.12.2, seen both in Firefox and Edge alike.

  1. Creating a flex-layout WHBoxLayout::setResizable leads to an immediate crash.
    Calling setResizable() while constructing the page (before it is actually shown/rendered) consistently aborts with Wt: fatal error: Cannot update widget without id. This suggests setResizable() triggers a client-side/DOM update too early (before widget IDs exist). This might be due to an initialization / first-render ordering issue. See also debug-log backtrace in FlexLayoutImpl.C attached.

Maybe due to:
https://redmine.emweb.be/issues/13670

  1. A WTreeView added as a stretch item inside a WHBoxLayout causes the horizontal size to grow indefinitely and triggers continuous Wt round-trips (non-converging layout/resize loop). Replacing WTreeView with a plain WContainerWidget works fine, and constraining the tree’s width (e.g. max-width) stops the loop. This suggests an interaction between WTreeView’s intrinsic sizing and the flex/box layout sizing algorithm.

Maybe similar:
https://redmine.emweb.be/issues/1409

I'm happy that I could extract the relevant parts into the sample code attached that allows to reproduce the issues.

Best,
Stefan

Files

Download all files
main.cpp (2.92 KB) main.cpp Stefan Bn, 02/04/2026 10:51 PM
Debug_FlexLayoutImpl.PNG (64.9 KB) Debug_FlexLayoutImpl.PNG Stefan Bn, 02/04/2026 10:51 PM

Related issues 2 (0 open — 2 closed)

Related to Bug #14314: WDialog not taking into account title bar being clearedClosedRomain Mardulyn02/09/2026

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Related to Bug #11875: WBoxLayout incorrectly calculates the size of scrollable widgetsClosedRomain Mardulyn08/15/2023

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SB Updated by Stefan Bn 7 months ago Actions
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 #1

And there is more :-(

  1. Assining a WHBoxLayout to WContainerWidget* Wt::WDialog::titleBar() leads to a crash when the dialog is shown. This used to work flawless in earlier versions.
auto dlg = this->addChild(std::make_unique<WDialog>());
auto titleHLayout = dlg->titleBar()->setLayout(std::make_unique<WHBoxLayout>());     // Crash

Debugger breaks at:

1 Wt::WTemplate::setCondition(std::stringconst&, bool) WTemplate.C 227 0x7ff805379373 
2 Wt::WDialog::render(Wt::WFlags<Wt::RenderFlag>)      WDialog.C   453 0x7ff80524aa2c

RM Updated by Romain Mardulyn 7 months ago Actions
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 #2

  • Status changed from New to InProgress
  • Assignee set to Romain Mardulyn
  • Target version set to 4.12.3

RM Updated by Romain Mardulyn 7 months ago Actions
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 #3

  • Related to Bug #14314: WDialog not taking into account title bar being cleared added

RM Updated by Romain Mardulyn 7 months ago Actions
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 #4

  • Related to Bug #11875: WBoxLayout incorrectly calculates the size of scrollable widgets added

RM Updated by Romain Mardulyn 7 months ago Actions
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 #5

  • Status changed from InProgress to Review
  • Assignee deleted (Romain Mardulyn)

MV Updated by Matthias Van Ceulebroeck 7 months ago Actions
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 #6

  • Assignee set to Matthias Van Ceulebroeck

RM Updated by Romain Mardulyn 7 months ago Actions
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 #7

  • Status changed from Review to Implemented @Emweb
  • Assignee changed from Matthias Van Ceulebroeck to Romain Mardulyn

RM Updated by Romain Mardulyn 7 months ago Actions
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 #8

  • Status changed from Implemented @Emweb to Closed
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