gcheckboxgroup: Constructor for checkbox group. A linked group of checkboxes,...
In gWidgets2: Rewrite of gWidgets API for Simplified GUI Construction

Description Usage Arguments Value Examples

Change handler for a GCheckboxGroupp is called when any of the checkboxes changes state.

The svalue methods refer to the selected values. By default these are the item values, coerced to characterq. When index=TRUE is specified, then the index is returned as an integer vector. For setting, one may also use a vector of logicals (which is recycled) for the index.

gcheckboxgroup(
  items,
  checked = FALSE,
  horizontal = FALSE,
  use.table = FALSE,
  handler = NULL,
  action = NULL,
  container = NULL,
  ...,
  toolkit = guiToolkit()
)

.gcheckboxgroup(
  toolkit,
  items,
  checked = FALSE,
  horizontal = FALSE,
  use.table = FALSE,
  handler = NULL,
  action = NULL,
  container = NULL,
  ...
)

## S3 method for class 'GCheckboxGroup'
addHandlerChanged(obj, handler, action = NULL, ...)

## S3 method for class 'GCheckboxGroup'
svalue(obj, index = NULL, drop = NULL, ...)

`items`	checkbox labels
`checked`	logical. Are values checked
`horizontal`	logical. If true displayed horizontally, else vertically
`use.table`	logical. If supported, and `TRUE` then uses a table widget with scrollbars
`handler`	A handler assigned to the default change signal. Handlers are called when some event triggers a widget to emit a signal. For each widget some default signal is assumed, and handlers may be assigned to that through `addHandlerChanged` or at construction time. Handlers are functions whose first argument, `h` in the documentation, is a list with atleast two components `obj`, referring to the object emitting the signal and `action`, which passes in user-specified data to parameterize the function call. Handlers may also be added via `addHandlerXXX` methods for the widgets, where `XXX` indicates the signal, with a default signal mapped to `addHandlerChanged` (cf. `addHandler` for a listing). These methods pass back a handler ID that can be used with `blockHandler` and `unblockHandler` to suppress temporarily the calling of the handler.
`action`	User supplied data passed to the handler when it is called
`container`	A parent container. When a widget is created it can be incorporated into the widget heirarchy by passing in a parent container at construction time. (For some toolkits this is not optional, e.g. gWidgets2tcltk or gWidgets2WWW2.)
`...`	These values are passed to the `add` method of the parent container. Examples of values are `expand`, `fill`, and `anchor`, although they're not always supported by a given widget. For more details see add. Occasionally the variable arguments feature has been used to sneak in hidden arguments to toolkit implementations. For example, when using a widget as a menubar object one can specify a parent argument to pass in parent information, similar to how the argument is used with gaction and the dialogs.
`toolkit`	Each widget constructor is passed in the toolkit it will use. This is typically done using the default, which will lookup the toolkit through `guiToolkit`.
`obj`	receiver object
`index`	NULL or logical. If `TRUE` and widget supports it an index, instead of a value will be returned.
`drop`	NULL or logical. If widget supports it, drop will work as it does in a data frame or perhaps someother means.

Returns an object of class GCheckboxGroup for which the following methods are overridden:

svalue Return the selected values or an empty character vector. If index=TRUE, returns indices of selected values.
svalue<- Set the selected values one of three ways: by label name, by a logical variable indicating which are selected (if ambigous, logical wins), if index=TRUE by the indices to select.
[ returns labels
[<- set the label values. Should be able to shorten or lengthen list

if(interactive()) {
  w <- gwindow("Selection widgets")
  g <- gvbox(cont=w)

  fl <- gformlayout(cont=g)
  gcheckbox("checkbox", checked=TRUE, cont=fl, label="checkbox")
  gradio(state.name[1:4], selected=2, horizontal=TRUE, cont=fl, label="gradio")
  gcheckboxgroup(state.name[1:4], horizontal=FALSE, cont=fl, label="checkbox group")

  bg <- ggroup(cont=g)
  gbutton("ok", cont=bg, handler=function(h,...) print(sapply(fl$children, svalue)))



}