Add QStyle::SH_SpinBox_StepModifier style hint

This patch allows the developer to pick which keyboard modifier
increases the number of steps a QAbstractSpinBox takes when the user
interacts with it.

The modifier can be either Qt::ControlModifier (default),
Qt::ShiftModifier or Qt::NoModifier. Qt::NoModifier disables the step
modifier. Note that on macOS, Control corresponds to the Command key.

Holding the modifier increases the step rate when:
- scrolling;
- pressing the up/down keys;
- pressing the spin box up/down buttons.

[ChangeLog][QtWidgets][QStyle] QStyle::SH_SpinBox_StepModifier allows
the developer to pick which keyboard modifier increases the number of
steps a QAbstractSpinBox takes for the following interactions:
scrolling, up/down keyboard keys and the spin box buttons. The
Qt::ShiftModifier can now be used, or the feature can be disabled
using Qt::NoModifier. Previously, only Qt::ControlModifier could be
used as the modifier.

Change-Id: Ib5518127e86a8f67798a9a1d6e860c6e35896e6f
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/widgets/styles/qstyle.cpp b/src/widgets/styles/qstyle.cpp
index 73a6554f1a..8006be8c27 100644
--- a/src/widgets/styles/qstyle.cpp
+++ b/src/widgets/styles/qstyle.cpp
@@ -2001,6 +2001,13 @@ void QStyle::drawItemPixmap(QPainter *painter, const QRect &rect, int alignment,
            Determnines if the spin box buttons are inside the line edit frame.
            This enum value has been introduced in Qt 5.11.
 
+    \value SH_SpinBox_StepModifier
+           Determines which Qt::KeyboardModifier increases the step rate of
+           QAbstractSpinBox. Possible values are Qt::NoModifier,
+           Qt::ControlModifier (default) or Qt::ShiftModifier. Qt::NoModifier
+           disables this feature.
+           This enum value has been introduced in Qt 5.12.
+
     \sa styleHint()
 */