entering two different note lengths on the same beat incompatible

I'm using version 0.9.5 on a Windows XP. I can't seem to find the solution to this problem anywhere. What I'm trying to do is enter in notes that are playing at the same beat but are of different lengths. For instance, the first note is a whole note for a 4/4 measure, but the rest of the left hand in the base clef waits an eighth rest and then plays a run, essentially a broken chord of eighth notes. I've tried to enter in the eighth notes first, and then add a whole note below it, but the program erases all the other notes. I've also tried entering the whole note first, and then add eighth notes on top, but again the whole note is erased. This event of breaking up one staff both visually and technically into different sections (for instance, having a sustained note in the bottom, while having a running part above that) happens a lot in music and is a common way of notating things to make it easier for the musician to read and play. I am not having trouble putting in notes of different lengths on top of each other (same beat) when one is in the base clef and one is in the treble clef.

Solution: The only thing I am able to do at the moment is to make a messy, complicated string of tied notes that exactly matches the note lengths that are going on in the rest of the staff (either base clef or treble clef). Is there a way to turn off the programming part that regulates the measure structure for a measure? It seems to not be able to comprehend two different durations and rhythms going on in the same staff for the same beat...it seems to think that is an error in its functions that require the measure to be the correct duration.

What it's doing basically is this:
When I put in a whole note (for instance) and then try and put an eighth note over it, the program calculates that the duration of both the whole note and the eighth note cannot be in a 4/4 measure, so it erases the previous measure to insert the whole note; or vice versa if I start with an eigth note. It seems to be adding up the notes, instead of thinking of them as a chord. The program is able to accept chords that are on top of each other, as long as they are all the same note length.

It would be useful if the program were able to 1) simply visually designate one note as another type, even if the midi player saw them as the same. This is because I'm using it primarily not to listen to it but to write music. or 2) the software were able to allow it, like an extra button to "promote" one of the eighth notes to a whole note in the same beat. 3) Another function of allowing this action would be to turn off the regulator that automatically inserts or erases notes or rests to enforce the specified duration of the measure. An error message could be allowed to pop up, but at least you would be able to override it and enter the music correctly, even if the midi player cannot play it.

1) above is just a work-around solution, which would work for me right now. 2) and 3) above are more useful, generalized solutions that would probably work for most people.

Please advise.