(Since the other answer doesn't actually describe what to do - I've copied it here in case the external link goes dead).
A process to do this is described in the following article, excerpted here:
(from https://visualstudiomagazine.com/articles/2010/03/02/redesign-ide-dialogs.aspx)
Redesign IDE Dialogs
By Karl E. Peterson 03/02/2010
...Well, there's a tool you can use to do modify these sorts of
settings to your heart's content. Resource Hacker is a freeware
utility to view, modify, rename, add, delete and extract resources in
32-bit Windows executables and resource files.
ResHacker offers a dialog tool that's extremely similar to Classic
VB's -- you just drag the dialog elements around, resizing them to
suit. Or you can edit the raw resource script, and watch the changes
play out in the dialog designer. Simply open the "Dialog" node in the
treeview, find the dialog you want to edit, and go to town. When
you're happy with the new design, press the "Compile Script" button,
then just do a File | Save to write the changes to disk. (Be sure to
make a backup of the original file, first...)
To modify the Classic VB Project-References dialog, open the
VB6IDE.DLL (or VB5IDE.DLL) file in ResHacker, find Dialog #4040 and
get to work.
The article also included two resource scripts - the modified, wider version, and also the original as a reference / backup.
Modified:
4040 DIALOG 0, 0, 455, 305
STYLE DS_MODALFRAME | WS_POPUP | WS_VISIBLE | WS_CAPTION | WS_SYSMENU
CAPTION "References"
LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
FONT 8, "Tahoma"
{
CONTROL "&Available References:", -1, STATIC, SS_LEFTNOWORDWRAP | WS_CHILD | WS_VISIBLE, 7, 7, 73, 8
CONTROL "", 5050, LISTBOX, LBS_NOTIFY | LBS_MULTIPLESEL | LBS_OWNERDRAWFIXED | LBS_HASSTRINGS | LBS_NOINTEGRALHEIGHT | WS_CHILD | WS_VISIBLE | WS_BORDER | WS_VSCROLL | WS_HSCROLL | WS_GROUP | WS_TABSTOP, 7, 19, 382, 235
CONTROL "OK", 1, BUTTON, BS_DEFPUSHBUTTON | WS_CHILD | WS_VISIBLE | WS_GROUP | WS_TABSTOP, 398, 18, 50, 14
CONTROL "Cancel", 2, BUTTON, BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE | WS_TABSTOP, 398, 40, 50, 14
CONTROL "&Browse...", 5051, BUTTON, BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE | WS_TABSTOP, 398, 61, 50, 14
CONTROL "&Help", 5052, BUTTON, BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE | WS_TABSTOP, 398, 240, 50, 14
CONTROL "Result", 5055, BUTTON, BS_GROUPBOX | WS_CHILD | WS_VISIBLE, 8, 260, 442, 37
CONTROL "Location:", -1, STATIC, SS_LEFT | WS_CHILD | WS_VISIBLE, 14, 271, 32, 8
CONTROL "", 5053, STATIC, SS_LEFTNOWORDWRAP | SS_NOPREFIX | WS_CHILD | WS_VISIBLE, 52, 271, 390, 8
CONTROL "Language:", -1, STATIC, SS_LEFT | WS_CHILD | WS_VISIBLE, 14, 282, 36, 8
CONTROL "", 5054, STATIC, SS_LEFTNOWORDWRAP | SS_NOPREFIX | WS_CHILD | WS_VISIBLE, 52, 282, 390, 8
CONTROL "&U", 4528, BUTTON, BS_OWNERDRAW | WS_CHILD | WS_VISIBLE | WS_GROUP | WS_TABSTOP, 416, 122, 14, 14
CONTROL "&D", 4529, BUTTON, BS_OWNERDRAW | WS_CHILD | WS_VISIBLE | WS_TABSTOP, 416, 149, 14, 14
CONTROL "Priority", -1, STATIC, SS_LEFTNOWORDWRAP | SS_NOPREFIX | WS_CHILD | WS_VISIBLE, 411, 139, 24, 8
}
Original:
4040 DIALOG 0, 0, 295, 204
STYLE DS_MODALFRAME | WS_POPUP | WS_VISIBLE | WS_CAPTION | WS_SYSMENU
CAPTION "References"
LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
FONT 8, "Tahoma"
{
CONTROL "&Available References:", -1, STATIC, SS_LEFTNOWORDWRAP | WS_CHILD | WS_VISIBLE, 7, 7, 73, 8
CONTROL "", 5050, LISTBOX, LBS_NOTIFY | LBS_MULTIPLESEL | LBS_OWNERDRAWFIXED | LBS_HASSTRINGS | LBS_NOINTEGRALHEIGHT | WS_CHILD | WS_VISIBLE | WS_BORDER | WS_VSCROLL | WS_HSCROLL | WS_GROUP | WS_TABSTOP, 7, 24, 193, 123
CONTROL "OK", 1, BUTTON, BS_DEFPUSHBUTTON | WS_CHILD | WS_VISIBLE | WS_GROUP | WS_TABSTOP, 238, 6, 50, 14
CONTROL "Cancel", 2, BUTTON, BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE | WS_TABSTOP, 238, 23, 50, 14
CONTROL "&Browse...", 5051, BUTTON, BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE | WS_TABSTOP, 238, 45, 50, 14
CONTROL "&Help", 5052, BUTTON, BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE | WS_TABSTOP, 238, 84, 50, 14
CONTROL "Result", 5055, BUTTON, BS_GROUPBOX | WS_CHILD | WS_VISIBLE, 7, 154, 281, 43
CONTROL "Location:", -1, STATIC, SS_LEFT | WS_CHILD | WS_VISIBLE, 35, 168, 32, 8
CONTROL "", 5053, STATIC, SS_LEFTNOWORDWRAP | SS_NOPREFIX | WS_CHILD | WS_VISIBLE, 75, 168, 198, 8
CONTROL "Language:", -1, STATIC, SS_LEFT | WS_CHILD | WS_VISIBLE, 35, 180, 36, 8
CONTROL "", 5054, STATIC, SS_LEFTNOWORDWRAP | SS_NOPREFIX | WS_CHILD | WS_VISIBLE, 77, 180, 196, 8
CONTROL "&U", 4528, BUTTON, BS_OWNERDRAW | WS_CHILD | WS_VISIBLE | WS_GROUP | WS_TABSTOP, 211, 62, 14, 14
CONTROL "&D", 4529, BUTTON, BS_OWNERDRAW | WS_CHILD | WS_VISIBLE | WS_TABSTOP, 211, 96, 14, 14
CONTROL "Priority", -1, STATIC, SS_LEFTNOWORDWRAP | SS_NOPREFIX | WS_CHILD | WS_VISIBLE, 206, 82, 24, 8
}
I've just tried this and it worked correctly. (Using VB6 Enterprise Edition + SP6.)