There is no reliable way to specify fixed-size panes in the Splitter control. If I specify that a pane should be fixed-size (with the 'size' property equal to an integer value, not a percentage), it simply does not work. Your competitors have Splitter controls that work fine.
See attached samples:
1) splitterTest_Syncfusion1.html: It has Header and Footer fixed-size panes with two Middle, percentage-sized panes. Initially it works, but if you resize the middle panes using the splitter, the footer no longer works as expected (its fixed-size is no longer respected). This is a bug.
2) splitterTest_Syncfusion2.html: It has Header and Footer fixed-size panes with a single Middle, percentage-sized pane. Initially it works, but if you resize the Footer pane using the splitter, the footer no longer works as expected (its fixed-size is no longer respected). This is a bug.
3) splitterTest_Syncfusion3.html: It has Header and Footer fixed-size panes with two Middle, percentage-sized panes, with relative sizing for the middle panes (I want the top pane to take up 30% of the remaining space and the bottom pane to take up 70% of the remaining space, after the Header and Footer have been positioned correctly). This does not work at all, because the Splitter control layout code is not written correctly. This is a bug.
I could go on and on with examples. Bottom-line is: there should be a way to have fixed-size panes using the Splitter control so that a fixed-size pane always remains fixed-size when the splitter is used to resize panes. Additionally, I should be able to specify relative sizes for percentage-sized panes, such as 30% and 70%. These are a very common use-cases for creating layouts, such as an IDE-style app. The layout code of the Splitter control needs to be re-coded so that fixed-size panes are sized and positioned first, then any remaining space is taken up by percentage-sized panes.