Suppose you have an editable page item, and you want to open a Modal Dialog where you then want to use the value of that page item (and return the edited value).
Since you need to set the session state of that item before opening the Modal Dialog, you cannot use a simple Redirect.
This can be done, but you need some Dynamic Actions and a page item to store the URL of the Modal Dialog.

Demo:

• Edit the value of Text (P1205_TEXT) on this page.
• Click on the Open Modal P1202 button.
• The DA Open Modal P1202 dynamic action sets the value of P1202_TEXT to the (edited) value of P1205_TEXT. Note that you could add this item to the URL which is generated in the next step, but then you would run the risk that the value is too long for the URL and will be truncated.
• The DA Open Modal P1202 dynamic action then sets the value of P1205_MODAL_P1202_URL to a URL for the modal page. Note the use of p_triggering_element which is set to the HTML DOM ID of the Open Modal P1202 button. Also note the values for Items to Submit and Items to Return.
• The DA Open Modal P1202 dynamic action then executes apex.navigation.redirect to open the modal page, using the URL stored in P1205_MODAL_P1202_URL.
• Edit the value of Text (P1202_TEXT) on the modal page.
• Click Save on the modal page, which submits the modal page.
• The page process Close Dialog on page 1202 closes the dialog, and returns the value of item P1202_TEXT.
• The DA Dialog Closed dynamic action then puts the value of P1202_TEXT into P1205_TEXT. Note the jQuery Selector which is set to the HTML DOM ID of the Open Modal P1202 button.

Item

Identification
	Name	P1205_TEXT
	Display As	Textarea

Item

Identification
	Name	P1205_MODAL_P1202_URL
	Display As	Display Only

Button

Name
	Button Name	P1205_OPEN_MODAL_P1202
	Text Label / Alt	Open Modal P1202
Layout
	Sequence	20
	Display in Region	Passing page items
Behavior
	Action	Defined by Dynamic Action
	Execute Validations	Yes
Advanced
	HTML DOM ID (= old Static ID)	p1205-open-modal-dialog-dom-id

Dynamic Action

Identification
	Name	DA Open Modal P1202
Execution Options
	Sequence	20
When
	Event	Click
	Selection Type	Button
	Button	P1205_OPEN_MODAL_P1202
Advanced
	Event Scope	Static
True Action
Identification
	Action	Execute Server-side Code
Settings
	Code	:P1202_TEXT := :P1205_TEXT; :P1205_MODAL_P1202_URL := apex_page.get_url ( p_page => 1202 , p_triggering_element => '#p1205-open-modal-dialog-dom-id' ) ;
Execution Options
	Sequence	10
	Fire On Initialization	No
True Action
Identification
	Action	Execute JavaScript Code
Settings
	Code	apex.navigation.redirect($v("P1205_MODAL_P1202_URL"));
Execution Options
	Sequence	20
	Fire On Initialization	No

Item

Note: This object is located on page 1202

Identification
	Name	P1202_TEXT
	Display As	Textarea

Button

Note: This object is located on page 1202

Name
	Button Name	P1202_SAVE
	Text Label / Alt	Save
Layout
	Sequence	20
	Display in Region	Settings
Behavior
	Action	Submit Page
	Execute Validations	Yes

Process

Note: This object is located on page 1202

Identification
	Name	Close Dialog
	Type	Close popup window
Process Point
	Sequence	10
	Process Point	On Submit - After Computations and Validations
	Run Process	Once Per Page Visit (default)
Settings
	Items to Return	P1202_TEXT

Dynamic Action

Identification
	Name	DA Dialog Closed
Execution Options
	Sequence	30
When
	Event	Dialog Closed
	Selection Type	jQuery Selector
	jQuery Selector(s)	#p1205-open-modal-dialog-dom-id
Advanced
	Event Scope	Static
True Action
Identification
	Action	Set Value
Settings
	Set Type	DIALOG_RETURN_ITEM
	Return Item	P1202_TEXT
	Suppress Change Event	N
Execution Options
	Sequence	10
	Fire On Initialization	No
Affected Elements
	Selection Type	Item
	Item(s)	P1205_TEXT