KiCad PCB EDA Suite
User Interface Guidelines

This document defines the guidelines for user interface development in KiCad. Developers are expected to following these guidelines as closely as possible when contributing user interface code to the KiCad project.

Text Capitalization

For all visible text used within KiCad, follow recommendations in the capitalization section in the writing style section of the GNOME User Interface Guidelines. This applies to all Menus, Titles, Labels, Tooltips, Buttons, etc.

The capitalization for the application names is KiCad, Eeschema, CvPcb, GerbView, and Pcbnew. All strings that have application names that are visible to the user should be capitalized this way. It's also a good idea use this capitalization in source code comments as well to prevent confusion of new contributors.

Capitalization Styles

There are two styles of capitalization are used in GNOME user interface elements: header capitalization and sentence capitalization. This section defines the capitalization style and when each type of capitalization should be used.

Header Capitalization

When using header capitalization all words are capitalized with the following exceptions:

  • Articles: a, an, the.
  • Conjunctions: and, but, for, not, so, yet ...
  • Prepositions of three or fewer letters: at, for, by, in, to ...

Sentence Capitalization

When capitalizing sentences, capitalize the first letter of the first word, and any other words normally capitalized in sentences such as proper nouns.

Capitalization Table

The following table indicates the capitalization style to use for each type of user interface element.

Element Style
Check box labels Sentence
Command button labels Header
Column heading labels Header
Desktop background object labels Header
Dialog messages Sentence
Drop-down combination box labels Sentence
Drop-down list box labels Sentence
Field labels Sentence
Text on web pages Sentence
Group box and window frame labels Header
Items in drop-down and list controls Sentence
List box labels Sentence
Menu items Header
Menu items in applications Header
Menu titles in applications Header
Radio button labels Sentence
Slider labels Sentence
Spin box labels Sentence
Tabbed section titles Header
Text box labels Sentence
Titlebar labels Header
Toolbar button labels Header
Tooltips Sentence
Webpage titles and navigational elements Header

Dialogs

This section defines how dialog boxes should be designed. The KiCad project uses the GNOME User Interface Guidelines for laying out dialogs. KiCad's dialogs must be designed with wxFormBuilder. As wxFormBuilder available in packages is likely to be a different version than what other developers have installed, it has been decided to use the version kept in a Github repository, branch wxFB3.5RC-1 to avoid version mismatch. When designing dialogs, follow the visual layout section of the GNOME User Interface Guidelines.

Escape Key Termination

Please note that the escape key termination only works properly if there is a dialog button defined with an ID of wxID_CANCEL or setting the escape button ID using wxDialog::SetEscapeID( MY_ESCAPE_BUTTON_ID ) is called during dialog initialization. The former is the preferred method for handling escape key dialog termination. There is a checkbox in wxFormBuilder for setting the "default" control, and this is the one fired when the "enter" key is pressed.

Dialog Layout with Sizers

Use wxWidgets "sizers" in all dialogs, no matter how simple they are. Using absolute sizing in dialogs is forbidden in KiCad. See the wxWidgets sizer overview for more information on using sizers. Configure the sizers so that as the dialog window is expanded, the most sensible use of the increased dialog window occurs automatically by the sizers. For example, in the DRC dialog of Pcbnew, sizers should be used to expand the text control to use the full available free window area, so that the user's view of the items in the text control is maximized as he/she expands the dialog window, making it easier to read more DRC error messages. In other dialogs without one component more important than the others, the sizers might be configured to position the controls to sensible positions near the perimeter of the increasingly larger dialog box, not necessarily leaving them all bundled tightly together. The dialog box should look nice at any size large enough to show all the user interface elements.

Avoid defining initial dialog sizes if possible. Let the sizers do their job. After the dialog is fit to the sizers, set the minimum size to the current size to prevent the dialog controls from being obscured when resizing the dialog. If the labels or text of the dialog controls are, set or changed at run time. Rerun wxWindow::Fit() to allow the dialog to re-size and adjust for the new control widths. This can all be done after the dialog is created but before it is shown or use class methods to re-size the dialog as required. Reset the minimum size to the updated dialog size.

Dialog windows should not exceed 1024 x 768 when displayed in a 13 point font. Note that the font used by end users is not something that you control from within the dialog, but for testing purposes please do not exceed this dialog size should the user have selected a font size of 13 points. If your dialog exceeds this limit, please redesign the dialog using tabs or some other paging method to reduce the size of the dialog.

Dialog Base Class

The KiCad project has a base class which most if not all dialogs should be derived from. When using wxFormBuilder, please add the following settings to the "Dialog" tab:

This will provide for an override of the Show( bool ) wxWindow() function and provide retentive size and position for the session. For more information, see the DIALOG_SHIM class source code.

Use tooltips to explain the functionality of each non-obvious control. This is important because the help files and the wiki often lag behind the source code.

Transferring Data To and From Controls

Dialog data must be transferred to the dialog controls on dialog initialization and transferred from controls when the dialog is dismissed by the default affirmative action (typically clicking the wxID_OK button) or the clicking the wxID_APPLY button. The wxWidgets dialog framework has support for this by using validators. Please read the wxValidator Overview in the wxWidgets documentation. In the past, data transfer was handled in various default button handlers virtually all of which were broken. Do not implement default button handlers in your dialog code. Use validators to transfer data to and from controls and allow the default dialog button handlers work the way they were designed.

Internationalization

To generate a list of strings occurring in a dialog, one needs to enable 'internationalize' checkbox in the project properties. Otherwise, it will not be possible to translate the dialog.

String Quoting

Often text strings will be quoted for display which use may used in controls that render HTML. Using angle brackets will cause grief for HTML rendering controls so text should be quoted with single quotes ''. e.g.:

  • 'filename.kicad_pcb'
  • 'longpath/subdir'
  • 'FOOTPRINTNAME'
  • 'anything else'