SweepFormula: Always use linestyle for sweep data

Experience has shown that users never want to have markers for sweep data.

Packages/MIES/MIES_SweepFormula_Helpers.ipf

@@ -621,6 +621,8 @@ static Function/WAVE SFH_GetSweepsForFormulaImpl(string graph, WAVE/WAVE selectD
 			colorGroup = GetUniqueInteger()
 			JWN_SetNumberInWaveNote(rangedSweepData, SF_META_COLOR_GROUP, colorGroup)
 
+			JWN_SetNumberInWaveNote(rangedSweepData, SF_META_TRACE_MODE, TRACE_DISPLAY_MODE_LINES)
+
 			EnsureLargeEnoughWave(output, indexShouldExist = index)
 			output[index] = rangedSweepData
 			index        += 1

Packages/tests/Basic/UTF_SweepFormula_Operations.ipf

@@ -1577,8 +1577,8 @@ End
 static Function TestOperationData()
 
 	variable i, j, numChannels, sweepNo, sweepCnt, numResultsRef, clampMode
-	string str, strSelect, epochStr, name, trace, wvList
-	string win, device
+	string str, strSelect, epochStr, name, trace, wvList, traces, traceInfos
+	string win, device, winBase
 	variable mode              = DATA_ACQUISITION_MODE
 	variable numSweeps         = 2
 	variable dataSize          = 10
@@ -1911,6 +1911,22 @@ static Function TestOperationData()
 		PASS()
 	endtry
 
+	// check that we use line style even for a couple of points
+	str     = "data(select(selrange([2, 6]), selsweeps(0), selchannels(AD6)))"
+	winBase = ExecuteSweepFormulaCode(win, str)
+	win     = winBase + "#Graph0"
+
+	traces = TraceNameList(win, ";", 1 + 2)
+	CHECK_EQUAL_VAR(ItemsInList(traces), 1)
+
+	trace = StringFromList(0, traces)
+	CHECK_PROPER_STR(trace)
+
+	traceInfos = TraceInfo(win, trace, 0)
+	CHECK_PROPER_STR(traceInfos)
+
+	CHECK(GrepString(traceInfos, "\bmode\(x\)=0\b"))
+
 	// workaround permanent waves being present
 	wvList = GetListOfObjects(GetDataFolderDFR(), "data*")
 	CallFunctionForEachListItem_TS(KillOrMoveToTrashPath, wvList)