---
name: "wxBookCtrlEvent"
section: "3erl"
platform: "linux"
package: "erlang-manpages"
version: "1:25.2.3+dfsg-1+deb12u4"
release: "Debian 12 (Bookworm)"
platforms: ["linux"]
url: "https://new.carta.tech/wxBookCtrlEvent"
---

# wxBookCtrlEvent(3erl)

Functions for wxBookCtrlEvent class

## NAME

wxBookCtrlEvent - Functions for wxBookCtrlEvent class

## DESCRIPTION

This class represents the events generated by book controls (*wxNotebook*, *wxListbook*, *wxChoicebook*, *wxTreebook*, *wxAuiNotebook*).

The PAGE\_CHANGING events are sent before the current page is changed. It allows the program to examine the current page (which can be retrieved with *getOldSelection/1*) and to veto the page change by calling *wxNotifyEvent:veto/1* if, for example, the current values in the controls of the old page are invalid.

The PAGE\_CHANGED events are sent after the page has been changed and the program cannot veto it any more, it just informs it about the page change.

To summarize, if the program is interested in validating the page values before allowing the user to change it, it should process the PAGE\_CHANGING event, otherwise PAGE\_CHANGED is probably enough. In any case, it is probably unnecessary to process both events at once.

See: *wxNotebook*, *wxListbook*, *wxChoicebook*, *wxTreebook*, *wxToolbook*, *wxAuiNotebook*

This class is derived (and can use functions) from: *wxNotifyEvent* *wxCommandEvent* *wxEvent*

wxWidgets docs: wxBookCtrlEvent

## DATA TYPES

```
wxBookCtrlEvent() = wx:wx_object()
```

```
wxBookCtrl() =
    #wxBookCtrl{type = wxBookCtrlEvent:wxBookCtrlEventType(),
                nSel = integer(),
                nOldSel = integer()}
```

```
wxBookCtrlEventType() =
    command_notebook_page_changed |
    command_notebook_page_changing | choicebook_page_changed |
    choicebook_page_changing | treebook_page_changed |
    treebook_page_changing | toolbook_page_changed |
    toolbook_page_changing | listbook_page_changed |
    listbook_page_changing
```

## EXPORTS

```
getOldSelection(This) -> integer()
```

Types:

This = wxBookCtrlEvent()\

Returns the page that was selected before the change, *wxNOT\_FOUND* if none was selected.

```
getSelection(This) -> integer()
```

Types:

This = wxBookCtrlEvent()\

Returns the currently selected page, or *wxNOT\_FOUND* if none was selected.

Note: under Windows, *getSelection/1* will return the same value as *getOldSelection/1* when called from the *EVT\_BOOKCTRL\_PAGE\_CHANGING* handler and not the page which is going to be selected.

```
setOldSelection(This, Page) -> ok
```

Types:

This = wxBookCtrlEvent()\
 Page = integer()\

Sets the id of the page selected before the change.

```
setSelection(This, Page) -> ok
```

Types:

This = wxBookCtrlEvent()\
 Page = integer()\

Sets the selection member variable.