Limit to # of Children on MDI form?

[rdeleon]

I have an application that uses an MDI form.

I have run into a problem where I am receiving an error message when I have 10 - 12 child forms open (the error message actually points to a usercontrol causing the problem, but I have exhausted my testing on the control and have not stumbled on a problem with the control). Most of the time my users will not have this many windows open, but I would like to know if there is a limit so I can account for that fact.

Any help is appreciated.

R De Leon

 

[lone84]

Hi Leon,

I do not think there is any limit to the number of MDI child. I open more than 10 forms when i am doing my project no problem with that

 

[rdeleon]

I think it depends on how "heavy" the child forms are.

I have several forms in my application. One form has about 20 controls on it and I can open over 100 forms with no problem. The form in question is a data entry/collection form and has about 120 controls (labels, cbo's, etc). I have been researching this error and have run across a few discussion forums where they mention a limit to the number of controls that are allowed per child
form but the limits discussed do not match my testing.

Anyway, if you get a chance, try adding a lot of controls on a MDI child form and see if you get a similar error.

I have plenty of memory available so I'm am pretty sure it is not an "out of memory" problem either.

Rene'

 

[jelloSoft]

Having plenty of memory doesn't mean you have plenty "ressources" free if you're under Win98/95/Me since these 16bits system are limited on the ressource side.....

The "ressources" of Windows are the number of handles available to user application (graphic and memory handles). And this number is..... fixed in Windows..... So you can have 1Gb of RAM and still have an "Out Of Memory" error if your forms are eating up ressources by for example having a lot of UserControl on the forms or not releasing picture objects.

just a clue

 

[rdeleon]

I'll admit upfront that I am not up to speed on handles.

You mention Win98/95/Me as 16 bit applications, the application is running on NT 4.0 workstations (32-bit?).

Do you know of any good resources that explain how handles are managed in NT?

Rene'