I am having the same issue but when creating comps at different frame rates or aspect ratios. It works fine in the floating panel but it falls apart when I am trying to make it dock-able. What would be a good approach to solving my issue at hand?

var button_margin           = 20,
    button_width            = 160,
    button_height           = 35,
    top_margin              = 80,
    panel_margin            = 10;

var l_button_left           = button_margin,
    l_button_right          = l_button_left + button_width,
    m_button_left           = l_button_right + button_margin,
    m_button_right          = m_button_left + button_width,
    r_button_left           = m_button_right + button_margin,
    r_button_right          = r_button_left + button_width,
    t_button_top            = top_margin,
    t_button_bottom         = top_margin + button_height
    m_button_top            = t_button_bottom + button_margin,
    m_button_bottom         = m_button_top + button_height,
    b_button_top            = m_button_bottom + button_margin,
    b_button_bottom         = b_button_top + button_height;

var win_width               = (panel_margin * 2) + (button_width * 3) + (button_margin * 4),
    win_height              = (panel_margin * 2) + (button_height * 3) +(button_margin * 3) + top_margin,
    panel_right             = win_width - panel_margin,
    panel_bottom            = win_height - panel_margin;
            
var win                     = new Window('palette', 'Floating Comp Creator'),
    panel                   = win.add('panel', [panel_margin, panel_margin, panel_right, panel_bottom]),
    divider0                = panel.add('panel', [l_button_left, panel_margin * 4, r_button_right, panel_margin * 4]),
    divider1                = panel.add('panel', [l_button_right + (button_margin / 2), t_button_top - (panel_margin * 2.5), l_button_right + (button_margin / 2), b_button_bottom]),
    divider2                = panel.add('panel', [m_button_right + (button_margin / 2), t_button_top - (panel_margin * 2.5), l_button_right + (button_margin / 2), b_button_bottom]),
    label0                  = panel.add('statictext', [m_button_left, panel_margin, m_button_right, button_height], 'Click to create the desired comp.'),
    label1                  = panel.add('statictext', [l_button_left + (button_width / 2) - 12, t_button_top - 22, l_button_right, t_button_top - 12], '16:9'),
    label2                  = panel.add('statictext', [m_button_left + (button_width / 2) - 12, t_button_top - 22, m_button_right, t_button_top - 12], '9:16'),
    label3                  = panel.add('statictext', [r_button_left + (button_width / 2) - 10, t_button_top - 22, r_button_right, t_button_top - 12], '1:1'),
    button0                 = panel.add('button', [l_button_left, t_button_top, l_button_right, t_button_bottom], '23.976 fps'),
    button1                 = panel.add('button', [l_button_left, m_button_top, l_button_right, m_button_bottom], '24 fps'),
    button2                 = panel.add('button', [l_button_left, b_button_top, l_button_right, b_button_bottom], '30 fps'),
    button9                 = panel.add('button', [l_button_left, m_button_top, l_button_right, m_button_bottom], '59.94 fps'),
    button10                = panel.add('button', [l_button_left, b_button_top, l_button_right, b_button_bottom], '60 fps'),
    button3                 = panel.add('button', [m_button_left, t_button_top, m_button_right, t_button_bottom], '23.976 fps'),
    button4                 = panel.add('button', [m_button_left, m_button_top, m_button_right, m_button_bottom], '24 fps'),
    button5                 = panel.add('button', [m_button_left, b_button_top, m_button_right, b_button_bottom], '30 fps'),
    button11                = panel.add('button', [l_button_left, m_button_top, l_button_right, m_button_bottom], '59.94 fps'),
    button12                = panel.add('button', [l_button_left, b_button_top, l_button_right, b_button_bottom], '60 fps'),
    button6                 = panel.add('button', [r_button_left, t_button_top, r_button_right, t_button_bottom], '23.976 fps'),
    button7                 = panel.add('button', [r_button_left, m_button_top, r_button_right, m_button_bottom], '24 fps'),
    button8                 = panel.add('button', [r_button_left, b_button_top, r_button_right, b_button_bottom], '30 fps');
    button13                = panel.add('button', [l_button_left, m_button_top, l_button_right, m_button_bottom], '59.94 fps'),
    button14                = panel.add('button', [l_button_left, b_button_top, l_button_right, b_button_bottom], '60 fps'),

win.bounds = [0,0,win_width,win_height];
win.center();   
win.show();

button0.onClick = function()
{
    app.project.items.addComp('horizontal - 16:9 - 23.976', 1920, 1080, 1, 30, 23.976);
}

button1.onClick = function()
{
    app.project.items.addComp('horizontal - 16:9 - 24', 1920, 1080, 1, 30, 24);
}

button2.onClick = function()
{
    app.project.items.addComp('horizontal - 16:9 - 30', 1920, 1080, 1, 30, 30);
}

button3.onClick = function()
{
    app.project.items.addComp('vertical - 9:16 - 23.976', 1080, 1920, 1, 30, 23.976);
}

button4.onClick = function()
{
    app.project.items.addComp('vertical - 9:16 - 24', 1080, 1920, 1, 30, 24);
}

button5.onClick = function()
{
    app.project.items.addComp('vertical - 9:16 - 30', 1080, 1920, 1, 30, 30);
}

button6.onClick = function()
{
    app.project.items.addComp('square - 1:1 - 23.976', 1080, 1080, 1, 30, 23.976);
}

button7.onClick = function()
{
    app.project.items.addComp('square - 1:1 - 24', 1080, 1080, 1, 30, 24);
}

button8.onClick = function()
{
   app.project.items.addComp('square - 1:1 - 30', 1080, 1080, 1, 30, 30);
}

button9.onClick = function()
{
    app.project.items.addComp('horizontal - 16:9 - 59.94', 1920, 1080, 1, 30, 59.94);
}

button10.onClick = function()
{
   app.project.items.addComp('horizontal - 16:9 - 60', 1920, 1080, 1, 30, 60);
}

button11.onClick = function()
{
    app.project.items.addComp('vertical - 9:16 - 59.94', 1080, 1920, 1, 30, 59.94);
}

button12.onClick = function()
{
    app.project.items.addComp('vertical - 9:16 - 60', 1080, 1920, 1, 30, 60);
}

button13.onClick = function()
{
    app.project.items.addComp('square - 1:1 - 59.94', 1080, 1080, 1, 30, 59.94);
}

button14.onClick = function()
{
   app.project.items.addComp('square - 1:1 - 60', 1080, 1080, 1, 30, 60);
}