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Divide by zero in /core/examples #1665

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Divide by zero in /core/examples#1665
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bugSomething isn't working correctly
@pancsta

Description

@pancsta
pancsta
opened on Apr 2, 2026

Describe the bug

Platform: Linux
System platform: Linux
App version: dev (unknown)
Core version: dev (unknown)
Time: 2026-04-02 20:07:07

panic: runtime error: integer divide by zero

goroutine 54 [running]:
runtime/debug.Stack()
	/usr/lib/go/src/runtime/debug/stack.go:26 +0x5e
cogentcore.org/core/core.handleRecover({0x15671e0, 0x26da340})
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/recover.go:44 +0x6b
cogentcore.org/core/core.(*renderWindow).eventLoop.func1()
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/renderwindow.go:416 +0x1f
panic({0x15671e0?, 0x26da340?})
	/usr/lib/go/src/runtime/panic.go:860 +0x13a
cogentcore.org/core/text/lines.(*Lines).layoutViewLine(0x36951c1f6a88, 0x0, 0x0, {0x36951c24a000, 0x38, 0x38}, {0x36951c1b2000, 0x1, 0x0?})
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/text/lines/layout.go:108 +0xdf1
cogentcore.org/core/text/lines.(*Lines).layoutViewLines(0x36951c1f6a88, 0x36951bee0cc0)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/text/lines/layout.go:29 +0x22d
cogentcore.org/core/text/lines.(*Lines).SetWidth(0x36951c1f6a88, 0x1, 0x0)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/text/lines/api.go:86 +0x131
cogentcore.org/core/text/textcore.(*Base).layoutAllLines(0x36951bbdf608)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/text/textcore/layout.go:84 +0xc6
cogentcore.org/core/text/textcore.(*Base).reLayoutAllLines(0x36951bbdf608)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/text/textcore/layout.go:104 +0x89
cogentcore.org/core/text/textcore.(*Base).SizeDown(0x36951bbdf608, 0x1)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/text/textcore/layout.go:145 +0x8c
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren.func1(0x26e3680?, {0x1ae7520?, 0x36951bbdf608?}, 0x36951bbdf608)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1042 +0x54
cogentcore.org/core/core.(*WidgetBase).forVisibleChildren(0x41a8000044324000?, 0x36951baa2250)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/widget.go:504 +0x1e3
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren(0x1?, 0x165bac0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1041 +0x3d
cogentcore.org/core/core.(*Frame).sizeDownChildren(0x36951be3f808?, 0x16c6500?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1068 +0x65
cogentcore.org/core/core.(*Frame).sizeDownFrame(0x36951be3f808, 0x1)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1129 +0x328
cogentcore.org/core/core.(*Frame).SizeDown(0x36951be3f808, 0x0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1096 +0x1c
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren.func1(0x26e3680?, {0x7f232ccf5800?, 0x36951be3f808?}, 0x36951be3f808)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1042 +0x54
cogentcore.org/core/core.(*WidgetBase).forVisibleChildren(0x4c6f7a?, 0x36951baa24b0)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/widget.go:504 +0x1e3
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren(0x46249f?, 0x165bac0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1041 +0x3d
cogentcore.org/core/core.(*Frame).sizeDownChildren(0x26e1700?, 0x16a3e60?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1068 +0x65
cogentcore.org/core/core.(*Frame).sizeDownFrame(0x36951c01ea88, 0x1)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1129 +0x328
cogentcore.org/core/core.(*Frame).SizeDown(0x36951c01ea88, 0x0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1096 +0x1c
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren.func1(0x26e3680?, {0x1ae5ae0?, 0x36951c01ea88?}, 0x36951c01ea88)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1042 +0x54
cogentcore.org/core/core.(*WidgetBase).forVisibleChildren(0x4c6f7a?, 0x36951baa2710)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/widget.go:504 +0x1e3
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren(0x46249f?, 0x165bac0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1041 +0x3d
cogentcore.org/core/core.(*Frame).sizeDownChildren(0x26e1700?, 0x16a3e60?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1068 +0x65
cogentcore.org/core/core.(*Frame).sizeDownFrame(0x36951bd99508, 0x1)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1129 +0x328
cogentcore.org/core/core.(*Frame).SizeDown(0x36951bd99508, 0x0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1096 +0x1c
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren.func1(0x26e3680?, {0x1ae5ae0?, 0x36951bd99508?}, 0x36951bd99508)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1042 +0x54
cogentcore.org/core/core.(*WidgetBase).forVisibleChildren(0x4c6f7a?, 0x36951baa2970)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/widget.go:504 +0x1e3
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren(0x46249f?, 0x165bac0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1041 +0x3d
cogentcore.org/core/core.(*Frame).sizeDownChildren(0x26e1700?, 0x16c5220?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1068 +0x65
cogentcore.org/core/core.(*Frame).sizeDownFrame(0x36951bd98008, 0x1)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1129 +0x328
cogentcore.org/core/core.(*Frame).SizeDown(0x36951bd98008, 0x0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1096 +0x1c
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren.func1(0x26e3680?, {0x1ae69c0?, 0x36951bd98008?}, 0x36951bd98008)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1042 +0x54
cogentcore.org/core/core.(*WidgetBase).forVisibleChildren(0x4c6f7a?, 0x36951baa2bd0)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/widget.go:504 +0x1e3
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren(0x46249f?, 0x165bac0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1041 +0x3d
cogentcore.org/core/core.(*Frame).sizeDownChildren(0x26e1700?, 0x16a3e60?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1068 +0x65
cogentcore.org/core/core.(*Frame).sizeDownFrame(0x36951bd84008, 0x1)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1129 +0x328
cogentcore.org/core/core.(*Frame).SizeDown(0x36951bd84008, 0x0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1096 +0x1c
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren.func1(0x26e3680?, {0x1ae5ae0?, 0x36951bd84008?}, 0x36951bd84008)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1042 +0x54
cogentcore.org/core/core.(*WidgetBase).forVisibleChildren(0x4c6f7a?, 0x36951baa2e30)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/widget.go:504 +0x1e3
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren(0x46249f?, 0x165bac0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1041 +0x3d
cogentcore.org/core/core.(*Frame).sizeDownChildren(0x26e1700?, 0x16a3e60?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1068 +0x65
cogentcore.org/core/core.(*Frame).sizeDownFrame(0x36951bd5f508, 0x1)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1129 +0x328
cogentcore.org/core/core.(*Frame).SizeDown(0x36951bd5f508, 0x0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1096 +0x1c
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren.func1(0x26e3680?, {0x1ae5ae0?, 0x36951bd5f508?}, 0x36951bd5f508)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1042 +0x54
cogentcore.org/core/core.(*WidgetBase).forVisibleChildren(0x4c6f7a?, 0x36951baa3090)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/widget.go:504 +0x1e3
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren(0x46249f?, 0x165bac0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1041 +0x3d
cogentcore.org/core/core.(*Frame).sizeDownChildren(0x26e1700?, 0x16c5220?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1068 +0x65
cogentcore.org/core/core.(*Frame).sizeDownFrame(0x36951bd4ea88, 0x1)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1129 +0x328
cogentcore.org/core/core.(*Frame).SizeDown(0x36951bd4ea88, 0x0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1096 +0x1c
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren.func1(0x26e3680?, {0x1ae69c0?, 0x36951bd4ea88?}, 0x36951bd4ea88)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1042 +0x54
cogentcore.org/core/core.(*WidgetBase).forVisibleChildren(0x4c6f7a?, 0x36951baa32f0)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/widget.go:504 +0x1e3
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren(0x46249f?, 0x165bac0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1041 +0x3d
cogentcore.org/core/core.(*Frame).sizeDownChildren(0x26e1700?, 0x16cd8e0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1068 +0x65
cogentcore.org/core/core.(*Frame).sizeDownFrame(0x36951bb59508, 0x1)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1129 +0x328
cogentcore.org/core/core.(*Frame).SizeDown(0x36951bb59508, 0x0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1096 +0x1c
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren.func1(0x26e3660?, {0x1ae6aa0?, 0x36951bb59508?}, 0x36951bb59508)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1042 +0x54
cogentcore.org/core/core.(*WidgetBase).forVisibleChildren(0x4c6f7a?, 0x36951baa3550)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/widget.go:504 +0x1e3
cogentcore.org/core/core.(*WidgetBase).sizeDownChildren(0x46249f?, 0x165bac0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1041 +0x3d
cogentcore.org/core/core.(*Frame).sizeDownChildren(0x26e1700?, 0x16c9e80?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1068 +0x65
cogentcore.org/core/core.(*Frame).sizeDownFrame(0x36951bd5a008, 0x1)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1129 +0x328
cogentcore.org/core/core.(*Frame).SizeDown(0x36951bd5a008, 0x0?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/layout.go:1096 +0x1c
cogentcore.org/core/core.(*Frame).layoutFrame(0x36951bd5a008, {0x0?, 0x0?})
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/render.go:145 +0x117
cogentcore.org/core/core.(*Scene).LayoutScene(0x36951bd5a008)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/render.go:130 +0x96
cogentcore.org/core/core.(*Scene).LayoutRenderScene(0x36951bd5a008)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/render.go:176 +0x18
cogentcore.org/core/core.(*Scene).doUpdate(0x36951bd5a008)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/render.go:249 +0x1f5
cogentcore.org/core/core.(*Stage).doUpdate(0x36951ca08000?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/stage.go:363 +0x57
cogentcore.org/core/core.(*stages).updateAll(0xc?)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/stages.go:258 +0xc5
cogentcore.org/core/core.(*renderWindow).renderWindow(0x36951e10b8c0)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/renderwindow.go:682 +0x12b
cogentcore.org/core/core.(*renderWindow).handleWindowEvents(0x36951e10b8c0, {0x1aecf18, 0x369539a13260})
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/renderwindow.go:482 +0x705
cogentcore.org/core/core.(*renderWindow).handleEvent(0x36951e10b8c0, {0x1aecf18, 0x369539a13260})
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/renderwindow.go:462 +0x465
cogentcore.org/core/core.(*renderWindow).eventLoop(0x36951e10b8c0)
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/renderwindow.go:430 +0xc5
created by cogentcore.org/core/core.(*renderWindow).goStartEventLoop in goroutine 1
	/home/tob/go/pkg/mod/cogentcore.org/core@v0.3.22-0.20260326010021-23998bfc5ad1/core/renderwindow.go:401 +0x65

How to reproduce

1 go run cogentcore.org/core/examples/demo@main
2 widgets - text editor
3 play with the middle divider left right

Example code



Relevant output




Platform


macOS
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