Fix HMI dialogs clipped by legacy Windows fonts

Why is the HMI configurator dialog clipped at the right edge?

The sub-panels inside the window request a legacy font named Helv, Windows substitutes the raster font MS Sans Serif for it, and those wider bitmap glyphs push the tag picker and its help button past the dialog's fixed width. The rest of the section explains the mechanism. Every sub-dialog in a Windows resource template carries its own font request. The main window here uses the DS_SHELLFONT style with the logical font "MS Shell Dlg". The embedded attribute panel, 122 px wide in the template, uses DS_SETFONT with "Helv". The dialog is fixed-size with no resize grip, so overflow hides controls instead of scrolling them. A test build widened the main template by 100 px, to 568 px, and recovered the missing controls, which measures the overflow the raster face adds.

Why do some dialogs clip while the rest of the window looks fine?

Windows lays the main window out with the logical font MS Shell Dlg, which maps to the TrueType face, while the embedded attribute panels ask for Helv or name MS Sans Serif outright, and only the second group clips. Read the symptoms this way:

• Tag picker and its question-mark button sit off the right edge. The embedded panel is rendering in the raster face; the registry change covers it.
• Text in the inner panel looks blocky and stays blocky when you change display scaling. Raster glyphs ship as fixed bitmaps, so scaling cannot redraw them.
• The outer window's text looks correct while the inner panel is wrong. Two font requests live in one dialog, and only the inner one resolves to Helv.
• A window such as Runtime Setup stays clipped after the registry change. It names MS Sans Serif explicitly, so only the vendor's fixed release repairs it.
• Your Windows 10 machines render the same configurator correctly. The FontSubstitutes defaults are identical there; the trigger is machine-specific and remains unidentified.
• A dialog fails to open at all. That is a different fault; start with HMI dialogs that will not open from POUs.

What is the difference between MS Sans Serif and Microsoft Sans Serif?

MS Sans Serif is a raster font, a set of bitmap glyphs drawn at fixed pixel sizes, while Microsoft Sans Serif is a scalable TrueType face, and dialog templates laid out with vector metrics overflow when handed the bitmaps. The two names describe different technologies that both ship with Windows for compatibility.

The FontSubstitutes key decides which physical face a requested name receives. On the affected Windows 11 build the defaults split: Helv points to MS Sans Serif and MS Shell Dlg points to Microsoft Sans Serif. That split is why half the window looks right and half of it breaks.

How do I fix the Helv font substitution in the registry?

Open regedit as an administrator, set the Helv value under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\FontSubstitutes from MS Sans Serif to Microsoft Sans Serif, export the key first, and restart so the new mapping takes effect. The steps:

1. Run regedit from an administrator account.
2. Export the key first: right-click FontSubstitutes, choose Export, and save the .reg file somewhere you can find it. That file is your rollback.
3. Open the Helv value, a REG_SZ string, and change its data from MS Sans Serif to Microsoft Sans Serif.
4. Leave MS Shell Dlg alone; it already points at the TrueType face.
5. Close regedit and restart the laptop.
6. Reopen the configurator and the dialog that clipped.

One safety note: this key sits in HKLM, so an edit in the wrong place can stop Windows starting, which is why you export first and touch only the Helv value.

Why are some dialogs still clipped after the registry change?

Some windows in the configurator name the raster font MS Sans Serif explicitly instead of asking for Helv, and the registry edits did not touch those windows, so no value under FontSubstitutes repairs them. In the configurator documented here, about 70 explicit MS Sans Serif references sit across its resource files, and the Runtime Setup window is one of the dialogs that uses them. The vendor's fixed release replaces every Helv and MS Sans Serif reference with Microsoft Sans Serif, and that release is the durable fix. Releases 10.3, 10.4 and 10.5 show the fault; the replacement lands in 10.6. Widening the templates by 100 px each, the main box to 568 px and the attribute panel from 122 px to 222 px, demonstrated the geometry, but editing the vendor's executable is the vendor's change to ship, and the fixed release makes it unnecessary on your machines.

What does the repair look like in an example scenario?

Take a fresh engineering laptop on Windows 11 running configurator version 10.3: the Dynamic Attributes dialog opens 468 px wide with its tag picker off-screen, the registry shows Helv set to MS Sans Serif, and the whole repair takes one edit plus a restart. Walk the numbers:

• Before: the main template is 468 px wide and the embedded attribute panel is 122 px. In the raster face the content needs about 100 px more than the template gives, 468 px + 100 px = 568 px, which is the width the widened test build needed. The tag picker and its question-mark button land past the edge and are unreachable.
• The edit: export FontSubstitutes, set Helv to Microsoft Sans Serif, restart.
• After: the dialog keeps its fixed width, and the tag picker and its button sit inside the edge. Every dialog that asks for a logical font now renders in the TrueType face.
• The remainder: Runtime Setup stays clipped because it names the raster font explicitly, one of roughly 70 such references. Update to the fixed release and those windows lay out too.

How do I check the fix worked and undo it?

Reopen the dialog that clipped: with the substitution corrected the tag picker and its help button sit inside the right edge and the text matches the face used in the rest of the window. Open a second window that used to clip and check it the same way. To undo the change, double-click the exported .reg file, restart, and Helv reads MS Sans Serif again.

When is the fault in the panel and not in the fonts?

If the text sizes correctly and you see lines, stripes or dropouts across the picture, the fault sits in the display chain, and a font substitution will not touch it. Diagnosing lines on an industrial control display walks that path. The dialog you are fighting builds the runtime screen; deciding what belongs on that screen is a separate question, and factory status display or operator HMI covers it. When the operator HMI is healthy and what the floor needs is a separate notice board that plays from a memory card, our shop-floor notice screens do that job; they are not HMIs and they take no video input.

What should you do first?

Change the registry value first, because it is one edit and a restart and it repairs every logical-font dialog in the configurator; then update to the fixed release, because only that repairs the windows that name the raster font explicitly.

Recommendation: Export the FontSubstitutes key, set Helv to Microsoft Sans Serif under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\FontSubstitutes, and restart; that covers every dialog that asks for a logical font. Update the configurator to the release that replaced the roughly 70 explicit MS Sans Serif references when windows such as Runtime Setup stay clipped after the restart.

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