Just drag the separator between the two areas.

It can't be dragged higher than this...

Do you mean that you want such big console window? Because you can tell Java to export the console output to a file.

On my 1280x1024 display on Windows 7, making the PDE window as tall as I can (with task bar at the bottom), I can display 35 lines of text in the console. Indeed, you cannot reduce the source window below 15 lines.
But, I just noticed, there are two very small arrows just below the left arrow of the source scrollbar (they don't appear on your screenshot). If you click on the down arrow, it will maximize the source area. If you click on the up arrow, it will maximize the console area.

Ok, i am currently busy with an project to minimize the console output window to put as much as possible source code on my screen, because i rather have as much as possible source code in my screen because i work in there. The console output is the result.

I currently created this, it catches the console output in a file and with a button i can read the console output. The errors are still in the console output window because i can't find a way to give text a different colour in the GUI textbox (i currently think that there is no option at all). It's also possible to put the textbox in a window, or a panel. I am currently busy with that, but i still have problems with windows and panels.

btw, i used Quarks GUI components library.

1. import guicomponents.*;
2. GTextField eventLog1;
3. GButton eventLog1up, eventLog1down, consolePromptloadout;
4. String OUT_FILE = "out.txt";
5. String ERR_FILE = "err.txt";
6. ArrayList events1 = new ArrayList();
7. void setup() {
8.   size(800,400);
9.   eventLog1 = new GTextField(this, "eventlog", 10, 150, 700, 100, true);
10.   eventLog1.tag = "eventLog1 -> ";
11.   // eventLog1up
12.   eventLog1up = new GButton(this, "Up", 10, 250, 50, 20);
13.   eventLog1up.tag = "Console SCROLL UP";
14.   eventLog1down = new GButton(this, "Down", 70, 250, 50, 20);
15.   eventLog1down.tag = "Console SCROLL DOWN";
16.   consolePromptloadout = new GButton(this, "Out", 200, 250, 50, 20);
17.   consolePromptloadout.tag = "consolePrompt READOUT";
18.   File outFile = sketchFile(OUT_FILE); 
19.   File errFile = sketchFile(ERR_FILE);   
20.   //  if (errFile.exists()) errFile.delete(); // not needed, it always overwrite
21.   try {
22.     System.setOut(new PrintStream(new FileOutputStream(outFile, false)));
23.     // System.setErr(new PrintStream(new FileOutputStream(errFile, false)));
24.   }
25.   catch (IOException e) {
26.     System.err.println("Error! "+e);
27.   }
28.   for (int i=0;i<100;i++) println("Console output line : "+i);
29. }
30. void draw() {
31. }
32. void handleButtonEvents(GButton button) {
33.   if (button == consolePromptloadout && button.eventType == GButton.CLICKED) { 
34.     File outFile = sketchFile(OUT_FILE); 
35.     String lines[] = loadStrings(outFile);
36.     //println("there are " + lines.length + " lines");
37.     for (int i=0; i < lines.length; i++) {
38.       //  System.err.println(lines[i]);
39.       String data = lines[i];
40.       events1.add(data);
41.     }
42.     eventLog1.setText(join((String[])events1.toArray(new String[events1.size()]), '\n'));
43.     // Scroll down until last event is visible.
44.     while(eventLog1.scroll(GTextField.SCROLL_DOWN));
45.   }
46.   if (button == eventLog1up && button.eventType == GButton.CLICKED) {
47.     eventLog1.scroll(GTextField.SCROLL_UP);
48.   }
49.   if (button == eventLog1down && button.eventType == GButton.CLICKED) {
50.     eventLog1.scroll(GTextField.SCROLL_DOWN);
51.   }
52. }