Catering for 'all' screen resolutions....whether higher or lower can be quite time-consuming...there are quite a few valid resolutions out there, not counting dual-screen varieties.
As an example, here is what I needed to do for my last LiteSTEP theme to make it 'totally' res-independent...
If ResolutionX = 800 and ResolutionY = 600
ChronosX 174
VWMX 368
*Slider "" 456 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 456 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 456 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
ElseIf ResolutionX = 1024 and ResolutionY = 768
ChronosX 286
VWMX 480
*Slider "" 568 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 568 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 568 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
ElseIf ResolutionX = 1152 and ResolutionY = 864
ChronosX 350
VWMX 544
*Slider "" 632 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 632 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 632 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
ElseIf ResolutionX = 1280 and ResolutionY = 768
ChronosX 414
VWMX 608
*Slider "" 696 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 696 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 696 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
ElseIf ResolutionX = 1280 and ResolutionY = 960
ChronosX 414
VWMX 608
*Slider "" 696 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 696 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 696 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
ElseIf ResolutionX = 1280 and ResolutionY = 1024
ChronosX 414
VWMX 608
*Slider "" 696 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 696 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 696 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
ElseIf ResolutionX = 1600 and ResolutionY = 900
ChronosX 574
VWMX 768
*Slider "" 856 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 856 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 856 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
ElseIf ResolutionX = 1600 and ResolutionY = 1024
ChronosX 574
VWMX 768
*Slider "" 856 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 856 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 856 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
ElseIf ResolutionX = 1600 and ResolutionY = 1200
ChronosX 574
VWMX 768
*Slider "" 856 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 856 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 856 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
ElseIf ResolutionX = 1920 and ResolutionY = 1080
ChronosX 734
VWMX 928
*Slider "" 1016 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 1016 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 1016 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
ElseIf ResolutionX = 1920 and ResolutionY = 1200
ChronosX 734
VWMX 928
*Slider "" 1016 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 1016 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 1016 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
ElseIf ResolutionX = 1920 and ResolutionY = 1440
ChronosX 734
VWMX 928
*Slider "" 1016 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 1016 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 1016 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
ElseIf ResolutionX = 2048 and ResolutionY = 1536
ChronosX 798
VWMX 992
*Slider "" 1080 -13 2 Volume1.png Volume-Handle.png #0ABHTIU [VOLUME] 0
*Slider "" 1080 -13 2 Volume2.png Volume-Handle.png #1ABHTIU [VOLUME] W
*Slider "" 1080 -13 2 Volume3.png Volume-Handle.png #2ABHTIU [VOLUME] 5
Else
EndIf