That is an attempt to access a memory vector where we expected to find a data structure that is not there anymore. So executing the previous code will bring a beautiful error message from OS X: What does this mean? The referenced Control object stored in a property was not marked as nil once it was out of scope because its containing window was closed, so it was simply unsafe (an dangerous!) to check or access its properties and methods through a simple verification of the type:ĭespite the object referenced through the property would have been released, this condition will execute the code inside the block resulting in a unexpectedly exit from the app! In fact inspecting the object via Xojo’s debugger shows that the reference is still there but it inner structure is void. This is, in fact, what happened to me recently while implementing a new feature in Snippery my productivity application where one of those unlikely but possible cases one of the objects left in an unstable state. Fortunately, we can keep this under control with the help of the WeakRef class.
However, sometimes the combination can simply reach unstable situations by the very nature of our applications and here is where failures can arise in memory management. From there, the interactions made by the user are those that determine how objects interact with each other via sending messages to each other (method calls), the access to properties and also the execution of events. You create objects (Instances) from the defined classes that act as templates and just let them roll.
Var grid = Ext.create(' Oriented Programming with Xojo, and in this case Event Oriented Programming as well, is simply wonderful. Try to exit edit field either by clicking on other cells or tabbing out and look at the console. To make things worse, after you tab thru few of this kind columns and nothing happens, you click on another cell instead of tabbing out, all the blur events for the fields you tabbed before are fired together. In numberfield, datefield and combobox type columns, the blur event is detected when you click another cell but is not detected when you tab out of the cell.
On textfield and textarea type columns, blur event is detected when you either tab out of the edit cell or you click on another cell. I need to detect when an edit cell is losing focus (blur event).
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