Lazarus known issues (things that will never be fixed)

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Other Interfaces

  • Lazarus known issues (things that will never be fixed) - A list of interface compatibility issues
  • Win32/64 Interface - The winapi interface for Windows 95/98/Me/2K/XP/Vista, but not CE
  • Windows CE Interface - For Pocket PC and Smartphones
  • Carbon Interface - The Carbon interface for Mac OS X
  • Cocoa Interface - The Cocoa interface for Mac OS X
  • Qt Interface - The Qt 4 interface for Unixes, Mac OS X, Windows, and Linux-based PDAs
  • GTK1 Interface - The gtk1 interface for Unixes, Mac OS X (X11), Windows
  • GTK2 Interface - The gtk2 interface for Unixes, Mac OS X (X11), Windows
  • GTK3 Interface - The gtk3 interface for Unixes, Mac OS X (X11), Windows
  • fpGUI Interface - Based on the fpGUI library, which is a cross-platform toolkit completely written in Object Pascal
  • Custom Drawn Interface - A cross-platform LCL backend written completely in Object Pascal inside Lazarus. The Lazarus interface to Android.

Platform specific Tips

Interfaces Development Articles

Win32/Win64 issues

TComboBox.Height

It's impossible to set an arbitrary height to a TComboBox under Windows. Use AutoSize to make sure the size is good on all platforms. (Although TComboBox.Height can be changed indirectly by changing TComboBox.Font size)

TButton's and TBitBtn's color cannot be changed

It's impossible to implement without making them owner drawn.

TProgressBar.Height

The Height of a TProgressBar cannot be smaller then 10 if a Windows Theme is used.

Associated bug report: http://bugs.freepascal.org/view.php?id=10626

MSDN Docs: http://msdn2.microsoft.com/en-us/library/bb760816(VS.85).aspx

TTrayIcon.Hint

TTrayIcon.Hint may have a maximum length of 127 WideChars (will usually be more then 127 Bytes in a UTF-8 string, but may be less too, depending on the string). It's a Windows limitation, which can't be worked around.

GTK 1 issues

Inconsistent internationalization support

GTK 1 always uses the default locale encoding to input and draw text and therefore adequate unicode support cannot be implemented for it.

TTabSheet.TabVisible property

TabSheet under gtk1 can either be fully hidden (with Tab) or fully visible (with Tab). There is no possibility to show TabSheet without it tab. Look at gtk1 sources (gtknotebook.c) for details.

TComboBox.DropDownCount property is ignored

What I consider a limitation in GTK1 & GTK2, but apparently it was a GTK design decision. For more details, see the following Mantis bug report: http://bugs.freepascal.org/view.php?id=1933

TStatusBar Panels

The TStatusPanel.Bevel and TStatusPanel.Alignment properties are ignored by all platforms except Windows. Maybe Qt supports them too, but is not confirmed. See the following message thread for details. http://lists.lazarus.freepascal.org/pipermail/lazarus/2010-January/048399.html

GTK 2 issues

TComboBox.DropDownCount property is ignored

What I consider a limitation in GTK1 & GTK2, but apparently it was a GTK design decision. For more details, see the following Mantis bug report: http://bugs.freepascal.org/view.php?id=1933

TStatusBar Panels

The TStatusPanel.Bevel and TStatusPanel.Alignment properties are ignored by all platforms except Windows. Maybe Qt supports them too, but is not confirmed. See the following message thread for details. http://lists.lazarus.freepascal.org/pipermail/lazarus/2010-January/048399.html

Carbon issues

Go to Carbon interface internals#Compatibility issues.

No 64-bits support

Carbon cannot be used to write 64-bits applications. Apple decided not to release a 64-bits version of Carbon. The migration path is writing a new interface in Cocoa.

QT issues

Qt license

  1. Qt up to and including version 4.4 could not be used to produce proprietary applications unless a Qt license is bought.
  2. Qt starting with 4.5 is now also published under the LGPL license, in addition to the commercial and GPL licenses. So, if you can comply with the LGPL, you can now avoid the commercial license.

TOpenDialog/TSaveDialog filter limitations

The display filter for TOpenDialog/TSaveDialog will always include the filtered extensions in parentheses. Qt always adds parentheses with the filtered extensions, so if this is already present, the interface will try to remove them. For more information see TQtWSFileDialog.GetQtFilterString on the Qt interface.

Win CE issues