JKQtExtras
a library of useful Qt widgets and tools
JKQTExtras Gallery
Form Organization/Layout
JKQTEVisibleHandleSplitter a QSplitter that has a really visible Splitter handle
JKQTEVerticalScrollArea

a scrollarea which shows only vertical scrollbars whenever possible (minimum widget size) and otherwise tries to maximize the size of the widget.

Progress Indicators
JKQTEProgressListWidget

displays a list of items with an icon next to each which indicates the current task performed on the item (e.g. not started, in progress, success, failed, ...)

JKQTEProgressListDialog

a dialog with a JKQTEProgressListWidget and a cancel button (optional)

JKQTEModernProgressWidget

a modern progress indicator widget

JKQTEModernProgressDialog

dialog, using JKQTEModernProgressWidget

Sliders ...
JKQTEColorSlider

a QSlider that allows to choose a color hue

Labels, Image Views, ...
JKQTEColorSampler a widget which display a color (sample)
JKQTEStarRatingWidget

a rating widget which displays five stars where the user may select how many are selected

Edit Fields
JKQTEEnhancedComboBox this QComboox descendent with en hanced features (e.g. can be set to read-only, editingFinished() signal, ...)
JKQTEDoubleEdit

this QLineEdit descendent implements a validating edit field that allows to enter floating point numbers with a possibly defined range

Buttons ...
JKQTEURLOpenToolButton specialized QToolButton which takes the contents of its buddy as webpage adress (URL) and opens it in the system's standard application
JKQTEDirectorySelectToolButton specialized QToolButton which allows to select a directory and saves its path in the buddy
JKQTEFileSelectToolButton specialized QToolButton which allows to select a file and saves its path in the buddy
JKQTEFileExecuteToolButton

specialized QToolButton which allows to open the file referenced by the buddy edit

Menus, ...
JKQTERecentFilesMenu

a special QMenu that allows to manage a list of recently loaded files

Data Models
JKQTECheckableStringListModel

a QStringListModel, which allows to check/uncheck each entry